JPH1137344A - High strength connecting method of pipe and connecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe connecting method of high strength which can be effectively used as a structure, while keeping a characteristic of the shape memory alloy joint of high workability, and provide a connecting device for the same. SOLUTION: When the pipes to be used as an underground structure after the connection, are connected by a shape memory alloy cylindrical joint 2, the through holes 3 are formed on the specific positions of the cylindrical joint 2, the pipes 1A, 1B to be connected are inserted from both sides of the joint 2, the joint 2 is heated at a temperature for recovering the shape, so that the cylindrical joint 2 is shrinked and the pipes are joined, then the screw holes are formed on the pipes at the positions corresponding to the through holes 3 of the cylindrical joint 2, and the bolts are screwed into the screw holes from the through holes 3 of the joint 2, to strongly fasten the pipe and the joint. The screw holes can be optionally formed on the pipe side in advance. The pipe connecting part exercises the high drawing strength and bending strength by the shrinkage force of the joint and the fastening force of the bolt or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for connecting pipes with high strength, and more particularly, to a protective structure (hereinafter simply referred to as a "structure") for underground objects such as underground structures and cables. The present invention relates to a high-strength connection method optimal for connection of a pipe used as a pipe and a connection device for implementing the method.

[0002]

2. Description of the Related Art When constructing and constructing a new tunnel or underground structure, an excavation is made in the soil to prevent the inner wall of the excavated portion from being collapsed by earth pressure. A so-called “curved boring method” for burying pipes accurately in the ground has been developed. (Corporation of Japan Construction Mechanization Association: Construction Mechanization Technology / Technical Examination Certificate Report, Curved Boring Equipment (TULIP Method), 199
4.8). In this curved boring method, arc-shaped pipes are sequentially connected, and finally arc-shaped pipes of a predetermined length are buried in parallel in a plurality of soils, and used as a support structure.

The present inventors have proposed a method of connecting pipes optimal for the above-mentioned curved boring method, in which a stepped pipe is connected by a shape memory alloy joint instead of a conventional connecting means by welding. A connecting means for firmly connecting the pipes with each other by the shrinkage force has been developed, and almost satisfactory results have been obtained in terms of workability (Japanese Patent Application No. 8-21025).
No. 6).

However, when used as a structure such as a pipe support for a tunnel having a large cross section, a pulling force or a bending stress acts on the pipe itself, so that the contraction force of the cylindrical joint made of a shape memory alloy is applied. May not be enough. Iron-based shape memory alloys are considered to be a type of steel, but because of the same austenitic structure as stainless steel, plastic deformation can be caused by relatively low stress compared to general steel, but it has the characteristics of a soft material, but plastic deformation Since the work hardening progresses with the progress of the steel, the fracture strength itself has a high value equal to or higher than the average high strength steel. In the case of ordinary piping, the pipe itself is often supported by other structures or buried underground, so the connection strength between the pipes depends on the shrinkage force due to heating of the shape memory alloy joint. In most cases, there is no problem.

[0005]

However, in applications where the pipe itself is used as a structure, the strength tends to be insufficient due to relying only on the shape memory effect as described above. The shape memory alloy pipe joint has a great feature that it can be easily installed and can be safely operated, especially in a narrow place. However, on the other hand, the fastening force of the shape memory alloy joint usually depends mainly on the frictional force between the outer surface of the pipe and the inner surface of the joint. If it is plastically deformed by an external force, it is rapidly lost. In particular, when a bending stress acts on the pipe being fastened, a strong force for expanding the joint in the radial direction is generated at the end face of the joint. Once the end is widened, the frictional force is reduced, and the fastening force is greatly reduced, thereby increasing the risk of the pipe being disconnected. In pipe connections as structures, this problem is critical.

[0006] In addition to the case where the pipe is used as an underground structure, there may be a mode in which the pipe is used as a case for protecting the buried object such as electric wires and various cables buried underground. In addition, a certain degree of pull-out strength and bending strength are required for the pipe connection part, and a sealing property for preventing intrusion of liquid and the like from the outside of the pipe is required.

[0007] In order to solve such a problem, the present invention provides a high-strength pipe connection method that can be effectively used as a structure after connection while utilizing the characteristics of a shape memory alloy joint having good workability. And a connection device therefor. In addition, another object of the present invention is to provide a pipe connecting means capable of exhibiting high sealing performance as required.

[0008]

According to a first aspect of the present invention, there is provided a method for connecting a pipe, comprising inserting a pipe to be fastened from both sides of a cylindrical joint made of a shape memory alloy having a through hole at a predetermined position. After heating the joint to a temperature that causes shape recovery, shrink the cylindrical joint and fasten the pipe,
A hole is formed on the pipe side at the position of the through hole of the cylindrical joint, and then a bolt from the through hole of the joint is screwed into the hole on the pipe side. As a result, the fastening force of the bolt is added to the contraction force of the cylindrical joint made of a shape memory alloy, and the connection strength between the pipes is increased. After the connection, the pipe is effectively used as a pipe structure underground or the like. The through hole of the cylindrical joint is desirably a tapered hole whose diameter decreases toward the center.

A second aspect of the present invention relates to a connection method using bolts in the same manner as in the first aspect. However, holes are provided in advance on the pipe side, and these pipes are inserted into a cylindrical joint to form a pipe screw hole. After temporarily temporarily fixing the joint and the pipe with a bolt in a state where the joint is aligned with the joint through hole, the joint is heated and contracted, and then the bolt is retightened. In this case, if the through hole on the side of the cylindrical joint is formed as a long hole extending in the circumferential direction, alignment by contraction of the joint becomes easy, and workability is improved.

According to the first and second aspects of the present invention, after the cylindrical joint made of a shape memory alloy is heated and contracted without using a fastening bolt, a knock pin is formed from the through hole of the joint to the hole on the pipe side. , The same connection is possible even if the connection is made (claim 3).

Further, in the present invention, after a sealing agent is previously applied or affixed to the inner surface of the cylindrical joint before fastening, a pipe is inserted from both sides of the cylindrical joint and connected, whereby a pipe connecting portion having excellent sealing properties is provided. Alternatively, it is possible to obtain a pipe connection portion with further increased connection strength (claim 4). In addition, the sealing agent used in the present invention refers to a resin-based sealing agent that exhibits a certain degree of adhesive performance as well as sealing performance.

Further, according to a fifth aspect of the present invention, there is provided a connecting device for providing a through hole at a predetermined position of a cylindrical joint made of a shape memory alloy, and an outer periphery of an end of a pipe to be connected. Then, a screw hole or a pin hole corresponding to the through hole of the cylindrical joint is formed, and a bolt or a knock pin is screwed or driven into the through hole of the joint. The through hole provided in the cylindrical joint is preferably an elongated hole extending in the circumferential direction, and the hole for the knock pin is preferably a tapered hole.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIGS. 1 to 3 show examples of fastening means using bolts, and particularly aim at improving both pull-out strength and bending strength. FIG. 1 shows two pipes 1A and 1B to be connected and a cylindrical joint (hereinafter simply referred to as a cylindrical joint) 2 for a pipe made of a shape memory alloy for inserting the pipe. 3 each at equal intervals along the circumference at a fixed distance from both ends (total 6
) Are formed. The number of the tapered holes (that is, the number of bolts) may be any number as long as it is two or more, but may be appropriately selected depending on conditions such as a diameter and a thickness of a pipe to be connected.

The cylindrical joint 2 is made of an iron-based shape memory alloy (for example, 28% Mn-6
% Si-5% Cr-Fe alloy). First, a cylindrical joint having an inner diameter slightly smaller than the outer diameter of the pipe to be connected is manufactured and subjected to memory treatment (heat treatment). Is obtained by enlarging the diameter. Further, in order to remarkably improve the shape memory performance, it is also possible to perform a certain processing and heat treatment at least once after the shape memory processing (training effect). In an embodiment to be described later, the cylindrical joint prepared first has the same configuration.

FIG. 2 shows a pipe 1A from both sides of a cylindrical joint 2;
1B illustrates a state in which a process of heating the cylindrical joint 2 to a predetermined temperature for causing the cylindrical joint 2 to recover its shape is performed after inserting and butting 1B. FIG. 3A shows a cross section at the position of the tapered hole 3 when the cylindrical joint 2 is contracted by heating, and the cylindrical joint 2 contracts and is in close contact with the pipe 1.
In this state, as shown in FIG. 3 (b), a hole is formed in the pipe 1 through a joint tapered hole 3 with a drill or the like, and a screw hole 4 is formed by threading the pipe hole. Next, as shown in FIG. 3 (c), a bolt (flat bolt) 5 having a tapered head is inserted from the tapered hole 3 and the screw hole 4 is formed.
Threaded cylindrical joint and pipe are fastened with a plurality of bolts.

FIGS. 4 to 6 show other embodiments of the fastening means using bolts. Two pipes 11 to be connected to FIG.
A and 11B and the cylindrical joint 12 are shown.
Three (six in total) tapered slots 13 are formed at regular intervals along the circumference at a fixed distance from both ends of the pipes 11a and 11b. Three screw holes 14 are formed at equal intervals along the circumference.

The tapered hole of the cylindrical joint 12 is a long hole 13 extending in the circumferential direction. However, since the cylindrical joint 12 finally contracts, it is assumed that the cylindrical joint 12 is an ordinary round hole. This is because it is difficult to perform accurate alignment with the hole, and if the hole is made long, the work becomes easy even if there is some deviation. As shown in FIG. 5, the hole 13 does not extend in the joint axial direction and has a normal tapered shape.

From both sides of the cylindrical joint 12, pipes 11A,
1B, and as shown in FIG.
3 and the screw holes 14 on the pipe side are roughly aligned.
As shown in (b), a further bolt 15 is inserted from the long hole 13 and screwed into the screw hole 14. At this time, the bolts 15 are not screwed in all, but are lightly screwed in to maintain the temporarily fixed state. In this state, the cylindrical joint 12 is heated to a predetermined temperature and contracted, and then the bolt 15 is tightened. This is Figure 6
This is the state shown in FIG.

In the two embodiments described above, the holes to be drilled on the pipe side are screw holes. However, when tapping bolts of a type which are self-threaded at the time of screwing are used as fastening bolts, screw holes are formed on the pipe side. A normal hole that is not processed may be formed. Also, apart from the fastening means of the type that screws bolts, instead of making the pipe side hole a threaded hole, it is formed into a simple tapered hole, and after the cylindrical joint is heated and shrunk, It is also possible to drive the knock pin into the hole on the pipe side and fasten it. In this case, it is desirable that the knock pin be made of a material such as mild steel or stainless steel that can be easily deformed.

In the illustrated embodiment, the hole on the cylindrical joint side has a tapered shape. However, if the head of the bolt (also the knock pin) is formed as a tapered countersunk bolt, the bolt can be tightened at the time of fastening. The head does not protrude from the surface,
This is because it is effective for connecting pipes to be laid in a borehole close to the pipe diameter. However, needless to say, a normal through hole having a constant diameter may be used instead of the tapered shape. Furthermore, in the description along the drawings of the present invention, the case where the joint outer surface after fastening projects from the pipe outer surface to avoid complexity is taken as an example, but as described above, the present invention is applied to a `` curved boring method ''. When applied, from the viewpoint of the interconnection of pipes laid in a borehole close to the pipe diameter,
As shown in the previously filed Japanese Patent Application No. 8-210256, at least one of a pipe and a joint is subjected to step processing,
Means for preventing the outer surface of the joint after contraction from protruding from the outer surface of the pipe as much as possible can also be applied.

Further, in the present invention, in addition to the pipe connection means using bolts and knock pins described above, a resin sealant having sealing performance and adhesive performance is applied in advance to the inner surface of the cylindrical joint made of shape memory alloy before fastening. Alternatively, after attaching the pipes, the pipes may be inserted from both sides of the joint, and then the joint may be heated and contracted to perform the connecting operation. As the resin-based sealant, an epoxy resin widely used as a sealant filler or an adhesive is suitable, but at least one exhibiting excellent sealing performance and preferably having good adhesion performance ( Usually, both are provided), but any may be used. According to the additional means using the resin-based sealant, even higher joint strength can be obtained, and in addition, applications requiring sealing properties of the pipe connection portion (for example, a pipe for surrounding and protecting an underground buried portion of a cable or the like). ) Is effective.

[0022]

【Example】

(Example 1) Pipe material: STK400 Dimensions: outer diameter 216 mmφ, wall thickness 18.5 mm, length 100
0mm, outer diameter 199.1mmφ at both ends (77
(The step length is formed by cutting the mm length part) Bolt holes: 3 places on the circumference of 45 mm from the pipe end, M
Fourteen threaded holes were drilled. Shape memory alloy joint material: 28% Mn-6% Si-5% Cr-Fe alloy Dimensions: Inner diameter 200.1 mmφ, wall thickness 9.7 mm, length 15
0 mm (after diameter expansion treatment) Bolt holes: Three holes were formed on the circumference of 30 mm from both ends of the joint, 16 mm in width at the bottom, 25 mm in length, and 90 mm in angle with a 90 ° angle. When sealant is not used and when epoxy resin is applied to the inner surface of the joint. Tightening method Insert pipes on both sides of the joint, loosely stop them with M14 "slatched bolt", and heat the joint by induction heating. Was heated to 300 ° C. After the inner diameter of the shape memory alloy joint shrank and the pipe was fixed, the bolts were further tightened to complete the fastening operation. On the other hand, in the case of using resin, fastening was performed by the same method as described above in a state where the epoxy resin was applied to the inner surface of the joint made of shape memory alloy after diameter expansion.

(Comparative Example 1) Pipe material: STK400 Dimensions: outer diameter 216 mmφ, wall thickness 18.5 mm, length 1000
mm Joint made of shape memory alloy Material: 28% Mn-6% Si-5% Cr-Fe alloy Dimensions: Inner diameter 200.1mmφ, wall thickness 9.7mm, length 150
mm (after diameter expansion treatment) Sealant not used and epoxy resin applied to the inner surface of the joint Fastening method Insert pipes on both sides of the joint, heat the joint to 300 ° C by induction heating, and use a shape memory alloy The inner diameter of the joint shrank and the pipe was fixed to complete the fastening operation. on the other hand,
In the case of using resin, fastening was performed by the same method as described above in a state in which the epoxy resin was applied to the inner surface of the shape memory alloy joint after diameter expansion.

Table 1 below shows a comparison of the strength and sealing performance of the connection obtained as a result of the pipe fastening operation performed in the above Examples and Comparative Examples. It can be seen that in the example using the bolt of the present invention, the pull-out strength is remarkably improved as compared with the case of the comparative example in which only the simple contraction force of the shape memory alloy joint is used. Also, the sealability was satisfactory when the sealant was applied.

[0025]

[Table 1]

[0026]

As described above, according to the connection method of the present invention, when connecting a pipe using a pipe joint made of a shape memory alloy, in addition to the fastening force due to the contraction force of the joint, the connection of the bolt and the like is performed. Because it can provide mechanical fastening force,
Connection with high pull-out strength and bending strength can be achieved. Therefore, it can be said that it is most suitable as a connecting means of a pipe that leaves the pipe as a structure, particularly as a connecting means applied to a curved boring method. In addition, when a resin-based sealing agent is used in combination, the joint strength is further improved, and excellent sealing properties can be exhibited. Therefore, it is particularly effective when applied to a connection portion where sealing properties are required. . On the other hand, according to the connection device according to the present invention, the above-described method can be effectively implemented, and a simple device can be used without requiring a large-scale means in terms of structure. It can be said that it is excellent.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state before connection in an embodiment of connection means according to the present invention.

FIG. 2 is a perspective view showing a case where the components shown in FIG. 1 are connected.

3A and 3B are cross-sectional views at the joint through-hole position at the time of connection shown in FIG. 2, wherein FIG. 3A shows a case where the joint shrinks, FIG. 3B shows a case where a threaded hole is formed in the pipe, and FIG. It shows the case where it is fastened.

FIG. 4 is a perspective view showing a state before connection in another embodiment of the connection means according to the present invention.

FIG. 5 is a longitudinal sectional view of the cylindrical joint in FIG. 4;

6A and 6B sequentially show a connection process of the connection means of FIG. 4;
(B) shows a state where the pipe and the joint are temporarily fixed with bolts, and (c) shows a state where the joint is contracted and bolts are tightened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,11 Pipe 2,12 Cylindrical joint for shape memory alloy pipe 3 Tapered hole 13 Tapered long hole 4,14 Screw hole 5,15 Bolt

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsunori Tomaru 2-3-13 Kanda Ogawacho, Chiyoda-ku, Tokyo M & C Building 4F Inside Awaji Sangyo Co., Ltd. (72) Inventor Takuo Moriya 2 Misakicho, Chiyoda-ku, Tokyo −5-3 Inside the Iron Construction Corporation (72) Inventor Taro Kasuya 2-5-3 Misakicho, Chiyoda-ku, Tokyo Inside the Iron Construction Corporation (72) Inventor Hiroshi Miki 2-26, Ogikubo, Suginami-ku, Tokyo 9-102 (72) Inventor Akio Miki 5-5-9 Asagaya Kita, Suginami-ku, Tokyo

Claims (5)

[Claims] When connecting a pipe to be used as a structure underground or the like after connection with a cylindrical joint made of a shape memory alloy, a through hole is provided at a predetermined position of the cylindrical joint and fastened from both sides of the joint. After the pipe is inserted, the joint is heated to a temperature that causes the joint to recover shape, the cylindrical joint is contracted, and the pipe is fastened.Then, a hole is formed in the pipe at the position of the through-hole of the cylindrical joint, and then the joint is penetrated. A high-strength pipe connecting method, wherein a bolt from a hole is screwed into a hole on the pipe side. 2. When connecting a pipe used as a structure underground or the like after connection with a cylindrical joint made of a shape memory alloy, a through hole is provided at a predetermined position of the cylindrical joint, and the pipe is also provided on the pipe side. A hole is provided at the position corresponding to the through hole of the joint, and after inserting the pipe to be fastened from both sides of the joint, the joint and the pipe are temporarily fixed lightly with bolts, and then heated to a temperature at which the joint will recover its shape. The method according to claim 1, further comprising: tightening the bolt after contracting the cylindrical joint to fasten the pipe. 3. The high-strength connection method for a pipe according to claim 1, wherein the hole formed on the pipe side is a tapered hole, and a knock pin is driven into the hole on the cylindrical joint side and the tapered hole on the pipe side for connection. 4. The high-strength connection method for a pipe according to claim 1, further comprising applying or attaching a sealant to the inner surface of the cylindrical joint before fastening, and then inserting the pipe from both sides of the cylindrical joint. 5. An apparatus for connecting a pipe to be used as a structure underground or the like after connection by a cylindrical joint made of a shape memory alloy, wherein a through hole is provided at a predetermined position of the cylindrical joint, and the pipe to be connected is connected. A high-strength connection device for a pipe, characterized in that a hole corresponding to the through hole of the cylindrical joint is formed on the outer periphery of the end of the pipe, and a bolt or a knock pin is screwed or driven into the through hole of the joint.