JP2505568B2 - Connection structure of lining steel pipe - Google Patents

Description

TECHNICAL FIELD The present invention relates to a connection structure for a lining steel pipe mainly used as a water supply / drainage pipe.

(Prior Art) In recent years, as a pipe material, a steel pipe having a synthetic resin lining on the inner surface thereof has been widely used.

The above-mentioned lining steel pipe, since the corrosion resistance which is a drawback of the steel pipe is captured by the lined synthetic resin, the corrosion resistance,
As an excellent piping material that has both strength, its application is expanding more and more.

However, when the above-mentioned lining steel pipe is used without subjecting the pipe end surface to the treatment of water resistance or corrosion resistance, for example, at the contact portion, water, chemicals, etc. penetrate into the interface between the steel pipe and the lining layer to increase the adhesive strength. However, there is a drawback that the lining layer is peeled off from the inner surface of the steel pipe and separated from the inner surface of the steel pipe to reduce the flow path.

In order to solve this drawback, the following method has been proposed.

As a first method, for example, in Japanese Utility Model Publication No. 58-27179, a short pipe with a collar, which can be expanded in diameter by heating, is inserted into the inside of a lining steel pipe at the connecting portion, and the lining is formed by heating and expanding the diameter. A method of coating the pipe end surface and the inner surface of a steel pipe in a watertight state has been proposed.

A second method is, for example, Japanese Patent Laid-Open No. 62-42.
In Japanese Patent No. 825, there is proposed a method in which a lining layer of a lining steel pipe is extended from an end pipe portion and the lining layer is folded back to the outer surface of the steel pipe to cover the end face of the lining pipe.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional technique, the first method can completely restore the original shape to the original shape of the collared short tube, which has been once diameter-reduced and solidified. Since it is difficult, there is a problem that the pipe end cannot be covered in a watertight state.

Further, in the second method, a special manufacturing process is required to extend the lining layer from the steel pipe, and a secondary process for folding back the lining layer is required.
There was a problem that the cost would be high.

(Means for Solving the Problem) The composite pipe of the present invention has been made to solve the problems of the above conventional products, in which the end portion of the lining steel pipe whose inner surface is coated with synthetic resin is expanded in diameter. The mouth part is formed,
A connection structure of a lining steel pipe in which another lining steel pipe is inserted into the receiving portion via packing, the pipe end portion of the lining steel pipe being inserted into the receiving portion is made of a shape memory polymer, A tube-end covering material with a U-shaped cross section is covered with an end surface coating that connects the inner and outer cylinders and the ends of both tubes in an annular shape. At the same time, the outer cylinder is formed by being radially expanded and deformed at room temperature, and after being coated on the tube end, the tube is heated and deformed at a temperature equal to or higher than the glass transition point to coat the tube end.

That is, a pipe end coating material made of a polymer having a shape memory property is inserted into a pipe end portion of a lining steel pipe, and the pipe end coating material is heated to a temperature of a glass transition temperature or higher to shrink the pipe end of the lining steel pipe. (EN) A lining steel pipe in which a portion is covered in a watertight state and water or a chemical solution does not enter from the end of the pipe.

The shape-memory polymer as referred to in the present invention is a polymer having a property of returning to its original shape by being heated to a glass transition point or higher, for example, polynorbornene,
Trans polyisoprene, polyurethane, butadiene
Examples include styrene copolymers.

The above shape memory polymers can be used alone or in combination with additives.

(Operation) The connection structure of the lining steel pipe of the present invention is made of a shape memory polymer, and a pipe end covering material having an insertion groove having a U-shaped cross section is inserted into the pipe end portion of the lining steel pipe, Since the pipe end is covered by heating and deforming the coating material to a temperature above the glass transition point, the pipe end is in a watertight state, there is no infiltration of water or chemicals from the pipe end, and the lining layer is from the steel pipe inner surface. Does not peel or come off.

(Examples) Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.

FIG. 1 is a cross-sectional view showing an example of a connecting portion in which a lining steel pipe 30 having a pipe end 33 covered with a pipe end coating material 40 is inserted into a receiving portion 10.

The pipe end covering material 40 is manufactured, for example, by injection-molding a shape memory polymer, and the shape thereof is the second shape.
As shown in the drawing, it has an insertion groove 41 which is annular and has a U-shaped cross section.

First, the pipe end covering material 40 is formed in a shape such that the outer diameter of the insertion groove 41 is slightly smaller than the outer diameter of the lining steel pipe 30 and the inner diameter thereof is slightly larger than the inner diameter of the lining steel pipe 30.

Therefore, the width of the insertion groove 41 is slightly smaller than the wall thickness of the lining steel pipe 30 (the wall thickness of the steel pipe 32 + the wall thickness of the lining layer 31).

 Next, the pipe end coating material 40 is subjected to plastic working at room temperature.

The plastic working is performed to expand the outer diameter of the insertion groove 41 to be slightly larger than the outer diameter of the lining steel pipe 30, and to reduce the inner diameter of the insertion groove 41 to be slightly smaller than the inner diameter of the lining steel pipe 30. .

By the plastic working, the insertion groove 41 is expanded,
The width of the insertion groove 41 is made slightly wider than the wall thickness of the lining steel pipe 30 (see FIG. 3).

As a specific method of plastic working, for example, by inserting a ring that can expand the diameter and a ring that can reduce the diameter into the insertion groove 41, and by expanding the diameter of one ring, the outer diameter of the insertion groove 41 can be mechanically increased. There is a method of mechanically reducing the inner diameter of the insertion groove 41 by enlarging and reducing the diameter of the other ring.

In this way, the pipe end covering material 40 having the expanded width of the insertion groove 41 is obtained by the plastic working.

Next, a method of coating the pipe end portion of the lining steel pipe 30 with the pipe end coating material 40 will be described.

First, the lining steel pipe is inserted into the insertion groove 41 of the pipe end covering 40.
After inserting the tube end portion 40 of the tube 40, the tube end covering material 40 is heated to the glass transition point or higher (see FIG. 3).

By heating, the pipe-end covering material 40 is deformed in an attempt to return to the shape before plastic working, so that the outer diameter of the insertion groove 41 is reduced and the inner diameter of the insertion groove 41 is expanded. The pipe 40 is mounted so as to tighten the pipe end 33 of the lining steel pipe 30, and surely covers the pipe end 33 (see FIG. 4).

Further, in order to make the coating with the pipe end coating material 40 more reliable, it is preferable that the insertion groove 41 of the pipe end coating material 40 is coated with, for example, a rubber adhesive.

Experimental Example-1 Before coating the pipe end coating material 40 on the pipe end portion 33, the following preliminary test was performed in order to test the heat deformability of the plastically worked pipe end coating material 40.

First, as the shape memory polymer, polynorbornene (manufactured by Bion Kasei Co., Ltd., trade name “No Solex”, glass transition point: about 35 ° C.) was used, and the tube end coating material 40 was injection molded at a temperature of 180 ° C.

Next, after inserting a diameter-enlarging and diameter-reducing stainless steel ring into the insertion groove 41 of the pipe end covering 40 for plastic working, the pipe end covering 40 is heated by blowing hot air at 60 °. As a result, it was confirmed that the pipe end covering material 40 was deformed to the dimensions before the plastic working.

The following table shows the dimensional measurement values of the pipe end covering material 40 (1) before plastic working, (2) after plastic working, and (3) after heat deformation.

Experimental Example-2 A pipe end coating material 40 having the same material, size and shape as those used in Experimental Example-1 was injection molded and then the pipe end coating material was manufactured.
40 was subjected to plastic working in the same manner as in Experimental Example-1.

After the rubber-based adhesive is applied to the insertion groove 41 of the pipe end coating material 40, the pipe end coating material 40 is lined with a vinyl chloride resin layer on the inner surface of the steel pipe (nominal diameter: 80A).
Insert it into the pipe end 33 (outer diameter: 89.1 mm, inner diameter: 80.7 mm),
Hot air of ℃ was blown with a blower to heat and deform the tube end 31.

After the tube end 33 was left standing for 24 hours, as shown in FIG. 1, the tube end 33 was inserted into the expanded mouth portion 10 and joined to form a connecting portion.

Water at 30 ° C. was passed through the above-mentioned connection portion at a flow rate of 40 / min for 3000 hours, but no infiltration of water from the pipe end 33 or peeling of the lining layer was observed.

Comparative Example-1 A connecting part was formed in the same manner as in Experimental Example-2 except that the pipe end coating material 40 was not coated on the pipe end 33, and water was passed under the same conditions as in Experimental Example-2. As a result, the lining layer was peeled off after passing water for 500 hours, and the flow channels were reduced.

Comparative Example-2 A connecting part was formed in the same manner as in Experimental Example-2, except that the pipe end portion 33 was coated with a rubber adhesive instead of the pipe end coating material 40, and the same as in Experimental Example-2. As a result of water being passed under various conditions, the adhesive layer was peeled off after passing water for 1000 hours, and water entered the pipe end 33.

(Effect of the invention) The connection structure of the lining steel pipe of the present invention, as described above,
A pipe end coating material made of a shape memory polymer and having an insertion groove having a U-shaped cross section is inserted into the pipe end portion of a lining steel pipe and heat-treated to reliably cover the pipe end portion. Therefore, water does not enter from the end of the pipe, and the lining layer does not peel off or come off.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a connecting portion of a lining steel pipe whose pipe end is coated according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of a pipe end coating material used in one embodiment of the present invention, FIG. 3 is a sectional view showing a state where the pipe end coating material of FIG. 2 is inserted into a plastically processed lining steel pipe, and FIG. 4 shows a state where the pipe end coating material of FIG. 3 is coated on the lining steel pipe. It is sectional drawing shown. 10 …… Receptacle, 20 …… Packing, 30 …… Lining steel pipe, 33 …… Pipe end, 40 …… Pipe end covering, 41 …… Insertion groove.

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A lining steel pipe having a lining steel pipe having an inner surface coated with a synthetic resin, the end of which is expanded to form a receiving port, and another lining steel pipe is inserted into the receiving port via packing. In the connection structure, at the pipe end of the lining steel pipe to be inserted into the receiving portion, an end face covering portion made of a shape memory polymer and connecting the end portions of the inner cylinder and the outer cylinder and both cylinders in a ring shape is provided. A tube end covering material having a U-shaped cross section is covered, and the tube end covering material is formed by the inner cylinder being contracted and deformed at room temperature and the outer cylinder being expanded and deformed at room temperature. A connection structure for a lining steel pipe, characterized in that after coating, the pipe end is heated and deformed at a temperature equal to or higher than the glass transition point, and the pipe end is coated.