JPH11324569A - Pipe connection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the construction in a short time, eliminate a necessity of heating a pipe up to a high temperature so as not to affect a pipe material, obtain high safety of the work, and ensure a sealing property of a pipe tightening part sufficiently when pipes installed in the ground are connected. SOLUTION: When a rear end of a preceding pipe embedded along a digged hole in the ground is connected with a tip of a following pipe through a joint 2 made of iron shape memory alloy, circumferential grooves corresponding to an inner face of the joint and an outer face of an end part of the pipe to be inserted therein are formed on these faces, respectively, an incomplete circular C ring 5 is inserted and held in either of the grooves of the joint and the pipe in advance and is inserted by positioning the pipe with the joint from both sides, the C ring is dropped in the respective corresponding grooves by advancing it while pushing and enlarging the C ring by the pipe (or while pushing and shrinking it by the joint), and then the joint made of shape memory alloy is heated and shrunk to connect the preceding pipe with the following pipe tightly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fastening pipes to be buried underground, and more particularly to a method for laying cable protection pipes and various pipes without excavation or for forming a ceiling or underground space such as a tunnel. When constructing a pipe structure that is a part of a structure such as a side wall (including this structure and a temporary structure)
The present invention relates to a fastening method and apparatus for connecting pipes to be propelled and inserted into the ground.

[0002]

2. Description of the Related Art For example, when constructing a pipe structure which becomes a part of a structure such as a ceiling or a side wall which forms an underground space such as a tunnel, a curved pipe having a circular arc-shaped fixed length is excavated in the ground. Propulsion insertion along the hole, sequentially connecting the leading end of the pipe and the leading end of the following pipe, to form an arc-shaped pipe structure of a predetermined length in the soil, and place this arc-shaped curved pipe in the soil After constructing in parallel, the surrounding area is frozen or solidified, and then the soil inside the pipe structure is excavated and removed to create a large-section tunnel or underground space, so-called curved boring method is proposed. Have been. In such a curved boring method, it is indispensable to connect the curved pipes to each other, but this connection requires not only a certain connection strength but also a sealing property, and at the same time, special skills are required for the connection work. It is required that the connection be completed in a short time without fail and a reliable connection be achieved.

Conventionally, this type of pipe connection means includes:
Welding, mechanical caulking, etc. have been put to practical use. However, welding can only be performed by special technicians, and high temperatures cause fumes and worsen the working environment.It takes a long time to join, and due to space limitations, the entire circumference of the pipe is welded under appropriate conditions. There are problems that are difficult to do. Also, mechanical caulking means is a method of inserting a pipe into the joint and fastening by depressing a plurality of locations on the circumference from the outside,
Although it has the advantage of short working time, it gives high deformation by concentrating locally, causing large residual stress,
There was a problem in securing the sealing performance of the fastening portion.

Recently, a diffusion bonding method using an amorphous metal foil has also been proposed, but in order to ensure the reliability of bonding with an extremely thin foil, the pipe end to be bonded must be formed with extremely high precision. It is necessary to keep the surface clean until finishing and joining. Further, for joining, it is necessary to heat to a high temperature exceeding 1000 ° C. while applying a certain pressure between the pipes to be joined, and to maintain the temperature at that temperature for a certain time, so that the work is not always easy. . In addition, the advantage that the heating temperature is lower than that of welding is that welding is heated to a temperature higher than the melting point at one point on the circumference, and the high temperature point moves sequentially on the circumference. Therefore, in diffusion bonding using amorphous metal foil, the entire circumference is simultaneously raised to a high temperature and a holding time is given, so the effect of high heat on the operator is far greater than welding, and the pipe itself also has this high heat. Therefore, there is a problem that the material is deteriorated.

The present inventors have conducted various studies to improve the problems of the conventional pipe connecting means, and as a result, have developed a method of using a joint made of an iron-based shape memory alloy for fastening a curved pipe. That is, since the inner diameter of a cylindrical iron-based shape memory alloy joint shrinks by about 3 to 4% by heating at about 300 ° C., the shrinking force is used to tightly fasten pipes inserted from both sides inside. It is. But,
In order to use iron-based shape memory alloy joints for joining pipes laid underground, it is necessary to further increase joint strength and ensure joint reliability. Circumferential grooves are formed on both sides, and C
A method and apparatus for attaching and joining rings has been proposed and filed (Japanese Patent Application No. 9-198725).

[0006]

However, the above-mentioned prior art has been effective as a joining means using a joint made of an iron-based shape memory alloy. It became clear that such inconveniences may occur. Hereinafter, a case will be described as an example where the C-ring is mounted in the concave groove on the joint side inner surface,
The reverse situation is exactly the same in the case where it is mounted in the groove on the outer surface of the pipe.

[0007] That is, in joining, a circular (substantially close to a perfect circle) C-ring mounted in a concave groove on the inner surface of the joint needs to have an inner peripheral side protruding from the inner surface of the joint by a certain height. When the joint made of the iron-based shape memory alloy contracts due to heating, the protruding portion enters the groove on the outer surface of the pipe on the other side, and the fastening is performed. It is desirable to take only large. On the other hand, if the difference between the outer diameter of the pipe and the inner diameter of the joint at a portion other than the concave groove is not ensured at least twice the protruding height, the pipe cannot be inserted into the joint.
Therefore, if the protrusion height is sufficiently secured, the difference between the inner diameter of the joint and the outer diameter of the pipe becomes large, and when the pipe is inserted into the joint, rattling occurs and the double concave groove is formed. With the position adjusted and held at the exact setting position,
It becomes difficult to enter the heating step. If heating is performed with the positions of the two concave grooves shifted, the C-ring is naturally fixed without entering the concave grooves, and the expected improvement in the fastening strength cannot be realized.

The present invention has been made in view of the above points, and when a pipe to be laid underground is fastened, the work can be performed in a short time as much as possible. It is an object of the present invention to provide a fastening method that does not affect the performance of the pipe, that has high work safety, and that can sufficiently secure the sealing performance of the pipe fastening portion as needed. Particularly, in pipe fastening using a ferrous shape memory alloy joint and a C-ring, a sufficient height of the C-ring is obtained, and more stable joining work and high fastening strength are to be obtained in actual operation. Make it an issue.

[0009]

According to a first aspect of the present invention, there is provided a method of fastening a pipe, comprising the steps of: When connecting the tip of the joint through an iron-based shape memory alloy joint, a corresponding circumferential groove is formed on the inner surface of the joint and the outer surface of the end of the pipe inserted into the joint, and one of the joint and the pipe is formed. Insert a non-circular C-ring into the groove in advance, align and insert the pipe into the joint from both sides, and push the C-ring forward with the pipe expanded or contracted with the joint, and into each corresponding groove. After the C-ring is dropped, the shape memory alloy joint is heated and shrunk to connect the preceding pipe and the succeeding pipe.

According to a second aspect of the present invention, in the method for fastening a pipe according to the first aspect, the non-circular C-rings are adjacent to each other at different distances from the center.
These consist of at least three locations in the ring circumferential direction. The shape of this C-ring will provide a sufficient protrusion height when inserting the pipe into the joint.

Further, according to a third aspect of the present invention, in the pipe fastening method according to the first or second aspect, the groove formed in the joint made of an iron-based shape memory alloy and the pipe has a rectangular cross section. The cross-section of the circular C-ring also has a shape corresponding to the groove cross-section, and is formed by tapering at least one of the inner edge of the pipe tip and the one-side edge of the inner surface of the C-ring. Such grooves and C-ring shapes facilitate insertion of the pipe and create high fastening strength.

According to a fourth aspect of the present invention, in the method for fastening a pipe according to the first aspect, the circumferential groove formed on the inner surface of the joint and the outer surface of the pipe is formed on a surface perpendicular to the joint axis and the pipe axis. The non-circular C-ring inserted into the groove is formed into an oblong shape so that the rotational force in the direction around the pipe axis is reliably transmitted between the connected pipes.

According to a fifth aspect of the present invention, as a fastening device for carrying out the above method, the leading end of the succeeding pipe is attached to the trailing end of the preceding pipe buried along the underground excavation hole. In a fastening device connected via a shape memory alloy joint, an inner diameter of the joint is made sufficiently larger than an outer diameter of a pipe, a circumferential groove is formed on an inner surface thereof, and the joint circle is formed on an outer surface of a pipe inserted into the joint. A circumferential groove corresponding to the circumferential groove is formed, and a non-true circular C-ring that is tightly inserted between the circumferential grooves when the joint into which the pipe is inserted is heated and shrunk is held in either the circumferential groove of the joint or the pipe. Claims are made for a pipe fastening device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. As shown in FIG. 1, each end of the two pipes 1A and 1B to be joined is inserted with a reduced diameter over a length that is longer than a length inserted into a cylindrical joint 2 made of an iron-based shape memory alloy (hereinafter simply referred to as a joint). A step is formed, a concave groove 3 having a rectangular cross section is provided at a predetermined position on the outer circumference of the step, and two cross sections corresponding to the pipe-side groove 3 are formed on the inner circumference of the joint 2. A rectangular groove 4 is provided.
At the time of connection, a non-circular C-ring 5 is inserted and held in either the groove 3 on the pipe side or the groove 4 on the joint side (in FIG. 1, the two concave grooves 4 on the joint side respectively). The C-ring is held), and the steps of the pipes 1A and 1B are inserted from both sides of the joint 2 so that the C-ring 5 falls into the groove 3 of the pipe. Then, both pipes are tightly fastened by the joint 2 and the C-ring 5.

FIGS. 2A and 2B show an example of the non-circular C-ring 5 used in the present invention.
After bending a hard steel wire such as spring steel with a rectangular cross section into a perfect circular shape, at least three or more locations on the circumference (four in the figure)
Is pressed into the inside of a circle over a certain length to form a non-circular shape, and then formed into a C-ring. For this reason, the non-circular C-ring 5 has portions different in distance from the center, that is, a portion 5a having a large distance from the center and a portion 5b having a short distance from the center are adjacent to each other. It has a shape that exists. In addition, the C ring 5
A taper 5c of approximately 10 ° to 30 ° is formed on one side edge portion of the inner surface, so as to function as a smooth guide when inserting a pipe, as described later.
When manufacturing the C-ring, it is also possible to manufacture the C-ring using a molding die having a predetermined shape.

An important feature of the present invention is the non-circular C
The function of the ring 5 will be described. For example, when the C-ring 5 as shown in FIG. 2 is inserted and held in the groove 4 on the inner surface of the joint 2 (the C-ring is made of a material having a spring property, the diameter of the ring is enlarged, and then the groove 4 is pressed and contracted. Can be easily held in the groove in the joint by inserting into the joint). As shown in FIG. 3, the outer side (back side) of the maximum outer diameter portion 5a of the C ring 5 is
It is pressed against the groove bottom of the joint groove 4 and the portion 5
The inside (ventral side) of a protrudes from the concave groove 4 (the dashed line is the groove depth) by a certain height. On the other hand, in a portion 5b having a smaller outer diameter adjacent to the maximum outer diameter portion 5a of the C ring 5, the back side thereof is in a state of floating from the groove bottom of the concave groove 4, and accordingly, in the maximum outer diameter portion 5a The shape protrudes more toward the inside of the joint than the protruding height. When the joint 2 is inserted and held in the concave groove 3 on the pipe side, on the contrary, the abdominal side of the minimum outer diameter portion of the outer diameter portion 5b of the C-ring 5 hits the concave groove 3 and the maximum outer diameter. The back side of the portion 5a protrudes greatly from the concave groove 3.

Therefore, when the tip of the pipe to be fastened into the joint 2 is inserted in the state shown in FIG. 3, the pipe tip is initially easily inserted into the joint 2 having a large diameter. At the position of C-ring 5. Here, when the pipe is pushed in by applying pressure, as shown in the right half of FIG.
In particular, the abdominal side of the larger protruding portion 5b of the C-ring 5 is pushed forward to advance. At this time, the presence of the taper 5c of the C-ring 5 assists the advance of the pipe. However, if necessary, it is desirable that the outer end of the pipe is also tapered as shown. Next, the pipe 1B that has continued to move forward
When the concave groove 3 coincides with the position of the C-ring 5, the ventral side of the C-ring 5 that has been pushed and spread on the outer surface of the pipe automatically falls into the groove, and stops the forward (or retreat) of the pipe there.

The state in which the C ring 5 enters both the concave groove 4 of the joint 2 and the concave groove 3 of the pipe 1B is a position where both grooves are accurately opposed to each other. Is always maintained during application. Due to the contraction caused by the heating of the joint 2, as shown in the left half of FIG. 4, the C ring 5 deforms into a perfect circular shape and tightly enters the concave grooves, and the fastening of the pipes 1A and 1B is completed. Thereby, the effect of the C ring 5 is maximized, and connection of a pipe having high fastening strength is realized.

Next, the embodiment shown in FIG. 5 differs from the embodiment shown in FIGS. 1 and 4 in that the groove of the joint and the pipe is located in a plane perpendicular to the joint and the pipe axis. Are inclined with respect to a plane perpendicular to the joint and the pipe axis. When excavating with a bit attached to the end of one of the pipes to be fastened, when turning the pipe at hand to transmit the torque to the bit, or when two pipes are aligned at a specific position in the circumferential direction The tilting method is effective when it is necessary to fasten the pipe (when the curved pipe is fastened without being twisted). In the fastening method as shown in FIG. 4, the strength against the pull-out force is sufficient, but it may be insufficient when transmitting the rotation of one pipe to the other pipe via the joint.

In FIG. 5, two pipes 11 to be fastened are shown.
It is necessary that the groove 13 formed on the outer surface of A, 11B and the groove 14 formed on the inner surface of the joint 12 have the same inclination angle θ (the angle with respect to a plane perpendicular to the pipe and the joint axis). In addition, the C ring 15 is formed in a non-circular shape and the shape shown in FIG. There are no particular restrictions on the shape of the concave groove or the cross section of the C-ring, and there is no difference from the above-described embodiment of the present invention. The larger the range of the inclination angle θ, the greater the resistance in the direction of rotation about the axis, but there are problems with workability and size.
Approximately 10 ° to 20 ° is appropriate.

The non-circular C-ring 5 is not limited to the one shown in FIG. 2, but may be, for example, one in which the number or range of portions having different outer diameters in FIG. 2 is changed, or the C-ring 25 shown in FIG. Such non-perfect circles, such as those formed by pushing a plurality of locations on the circumference toward the center to form portions with different outer diameters, arcs having any curvature, combinations of curves, or combinations of these with straight lines In some cases, it may be polygonal. In other words, if there are at least three protrusions on the circumference of the C-ring that require a certain amount of insertion force when inserting a pipe into the joint, in other words, exert a suitable resistance. Good. The C-ring is preferably made of a springy steel wire. The cross-sectional shape is not limited to the illustrated rectangular cross-section, and may be circular or elliptical, but a higher fastening strength is obtained. Is preferably a combination of a ring with a rectangular cross section and a rectangular groove.

In the illustrated example, the outer periphery of the end of the pipe to be inserted into the joint is externally machined to form a step. This is to minimize the extent to which the fastening portion projects outside the joint. In order to reduce the number, especially when there is no problem even if the projection is made, such a step is unnecessary.

[0023]

Example (Example 1) [Conditions] Joint material: 28Mn-6Si-5Cr-Fe-based shape memory alloy Size: 125.5 outer diameter × 115.5 inner diameter × 120.0
Length [mm] Groove: 5.1 width x 2.0 depth [mm], 3 from both ends of the joint
2 lines at 0mm position ・ Pipe material: STK400 Size: 100A (114.3mmφ × 6.0mmt) Insertion step: Cutting to outer diameter 113.5mmφ Groove: 6.0 width × 1.2 depth [mm Non-circular C-ring Material: SWRH72A Shape: Ring shape of FIG. 2, 3.0 mmφ circular cross section (A type), 4.0 W × 3.0 h (mm), 20 ° to one side of inner surface
・ Taper (B type) ・ Heating means Heat to 300 ° C with induction heating coil

[Results] Under the above conditions, the C-ring was placed in the groove on the joint side, and the pipe was inserted from both sides of the joint. As a result, the C-ring fell smoothly and automatically into the groove on the pipe side. Setting to the proper position was easily performed. At this time, the insertion force of the pipe into the joint was about 0.6 kN for the A ring and about 2 kN for the B ring. In addition, the strength of the fastening portion is 1.6 times or more the strength of the A-type ring without the ring (other conditions are the same), and about 2 times or more the strength of the B-type ring than the no ring. confirmed.

(Example 2) [Conditions] Joint material: 32Mn-6Si-Fe-based shape memory alloy Size: 280.9 outer diameter × 264.9 inner diameter × 180.0
Length [mm] Groove: 9.0 width x 3.5 depth [mm], 3 from both ends of the joint
2 lines at 5mm position ・ Pipe material: STK400 Size: 250A (267.4mmφ × 9.3mmt) Insertion step: Cutting to outer diameter 261.4mmφ Groove: 10.0 width × 2.0 depth [mm Non-circular C-ring Material: SWRH72A Shape: Ring shape of FIG. 2 (outer diameter 271.9 m of 5a portion)
m, inner diameter of 5b part 256.4 mm), 8.0 in rectangular cross section
W × 5.0h (mm) 20 ° taper on one side of inner surface ・ Heating means Heat to 300 ° C with induction heating coil

[Results] As in the first embodiment, the pipes were inserted and fastened without any trouble. The insertion force when inserting the pipe was about 3 kN. It was confirmed that the fastening strength was twice or more the strength of no ring and no ring (other conditions were the same).

(Embodiment 3) [Conditions] Joints and pipes are the same as in Embodiment 2. The C-ring used was the same material as the ring of Example 2 and processed into an oblong shape. However, the inclination angle θ was set to 15 °. [Results] There was no particular problem in the insertion of the pipe except that it was required that the circumferential position of the groove of the joint and the groove of the pipe be accurately aligned. The insertion force is about 1 kN, the fastening strength is 1.8 times or more compared to the case without the ring, and
The resistance around the axis was sufficient, and the rotational force between the pipes could be transmitted almost as it was.

[0028]

According to the pipe fastening method according to the present invention described above, the following effects can be expected. When a pipe is fastened with an iron-based shape memory alloy joint with a non-circular C-ring interposed, the protrusion height of the C-ring can be sufficiently taken, so that the fastening is reliable and the joint strength after heat shrinkage of the joint is also high. improves. When the pipe is inserted into the joint, the pipe can be reliably stopped at an appropriate position without paying special attention to the insertion length, so that the fastening can be performed without insufficient insertion or an unstable insertion state. Even if the difference between the inner diameter of the iron-based shape memory alloy joint and the outer diameter of the pipe is made as large as possible, there is an appropriate resistance when inserting the pipe, and the C-ring that is bent at the appropriate position Since it is restored at a stretch and falls into the concave groove, it can be clearly confirmed that it has been set at the proper position. Further, there is no fear of shifting from the proper position during the heating operation, so that all fastening operations can be performed in a stable state. Since the fastening work is easy and sufficient fastening strength is obtained, it is most suitable for joining curved pipes buried underground. When the pipe is fastened by inclining the non-circular C-ring, it is possible to effectively transmit not only the axial fastening force but also the rotational force in the direction around the axis between adjacent pipes.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a pipe fastening method according to the present invention.

FIG. 2 shows a specific example of a non-circular C-ring used in the method of the present invention, wherein (a) is a plan view and (b) is an enlarged sectional view thereof.

FIG. 3 is a partial detailed view showing a state where a non-circular C-ring is held in a groove on the joint side.

FIG. 4 is a view for explaining a process when the fastening method of the present invention is performed.

FIG. 5 is an explanatory view showing another embodiment of the method of the present invention.

FIG. 6 is a plan view showing another example of the non-true circular C-ring used in the present invention.

[Explanation of symbols]

 1A, 1B, 11A, 11B Pipe 2, 12, 22 Cylindrical joint made of iron-based shape memory alloy 3, 13 Pipe-side groove 4, 14 Joint-side groove 5, 15, 25 Non-perfect C-ring 5a Maximum C-ring Outer part 5b Minimum outer part of C ring 5c Inner diameter taper part of C ring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsunori Tomaru 2-3-13 Kanda Ogawamachi, Chiyoda-ku, Tokyo M & C Building 4F Inside Awaji Sangyo Co., Ltd. (72) Inventor Taro Kasutani 2 Misakicho, Chiyoda-ku, Tokyo −5-3 Inside Tekka Construction Corporation (72) Inventor Tsuneo Obata 2-5-3 Misakicho, Chiyoda-ku, Tokyo Inside Tekka Construction Corporation (72) Inventor Hiroshi Miki 9-102 (72) Inventor Yoshito Okada 4-21-510 Toyookacho, Tsurumi-ku, Yokohama-shi, Kanagawa

Claims (5)

[Claims] At the time of connecting the front end of a succeeding pipe to the rear end of a preceding pipe buried along an underground excavation hole via a joint made of an iron-based shape memory alloy, the joint is inserted into the inner surface of the joint. On the outer surface of the end of the pipe to be formed, a corresponding circumferential groove is formed, and a non-circular C-ring is inserted in advance in one of the joint and the pipe, and the pipe is aligned with the joint from both sides. After inserting the C ring into the corresponding groove by pushing or expanding the C ring with a pipe or compressing and shrinking the joint with a joint, the shape memory alloy joint is heated and shrunk to form a leading pipe and a succeeding pipe. And a method of fastening a pipe. 2. The pipe fastening method according to claim 1, wherein the non-circular C-rings are adjacent to each other at different distances from the center, and are present in at least three places in the circumferential direction of the ring. 3. A groove formed in an iron-based shape memory alloy joint and a pipe has a rectangular cross section, and a cross section of a non-circular C-ring also has a shape corresponding to the groove cross section. The pipe fastening method according to claim 1 or 2, wherein a taper is formed at one of the inner surface and one edge portion of the inner surface of the C-ring. 4. A circumferential groove formed on the inner surface of the joint and the outer surface of the pipe is formed to be inclined with respect to a plane perpendicular to the joint axis and the pipe axis, and a non-circular shape inserted into the groove. C
The pipe fastening method according to claim 1, wherein the ring has an oval shape. 5. A fastening device for connecting a leading end of a succeeding pipe to a trailing end of a preceding pipe buried along an underground excavation hole through an iron-based shape memory alloy joint. While making it sufficiently larger than the outer diameter and forming a circumferential groove on the inner surface thereof, forming a circumferential groove corresponding to the joint circumferential groove on the outer surface of the pipe inserted into the joint, when the joint into which the pipe is inserted is heated and shrunk, A pipe fastening device characterized in that a non-true circular C-ring that is tightly inserted between the circumferential grooves is held in either a joint or a circumferential groove of the pipe.