JPS5949885B2 - Manufacturing method of synthetic resin lined metal pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a synthetic resin-lined metal tube.

Insert a small diameter long synthetic resin pipe into a large diameter long metal pipe,
A synthetic resin lined pipe in which both parts are bonded together with an adhesive is already known.

Furthermore, methods for manufacturing such lined pipes are already known. Various methods were used to manufacture the above-mentioned lined tubes, including:

The first method is to apply adhesive to the inner surface of the metal tube or the outer surface of the synthetic resin tube, and then expand the inner diameter of the synthetic resin tube.
This method brings the resin tube into close contact with the inner surface of the metal tube. The second method is to apply an adhesive to the inner surface of the metal tube or the outer surface of the synthetic resin tube, and then reduce the outer diameter of the metal tube to bring the metal tube into close contact with the outer surface of the resin tube. The third method is
This is a method in which a synthetic resin pipe is inserted into a metal pipe, and then a stock solution for producing urethane resin is injected into the gap between the two pipes, and the stock solution is foamed and hardened to be integrated. Among these methods, method 1 and method 2 require large-scale equipment because they require expanding the inner diameter of the synthetic resin pipe and reducing the outer diameter of the metal pipe, respectively. It also has the disadvantage of being complicated to operate.

In the third method, it is not easy to inject the stock solution evenly into the gap between both tubes, and the gap between the synthetic resin tube and the metal tube is inevitably large, making it difficult to use a high-quality lining tube. It has the disadvantage that it cannot be obtained. Therefore, there was a need to devise a method for manufacturing lined pipes of high quality more easily. The inventor previously proposed a method for manufacturing a lining pipe in response to the above-mentioned needs.

The manufacturing method uses a long metal tube with a large diameter and a long synthetic resin tube with a small diameter that can be inserted into the long metal tube, and makes the difference between the inner diameter of the metal tube and the outer diameter of the resin tube small, Apply foaming adhesive to the inner surface of the metal tube or the outer surface of the resin tube, insert the resin tube into the metal tube immediately after application, allow the adhesive to foam and harden, and unite both tubes. It is something. However, to implement this method, after applying the foam adhesive,
It is necessary to immediately insert the resin tube into the metal tube and hold the resin tube in the center position within the metal tube quickly and securely.
This required special ingenuity. This invention was created in response to such a need. The inventor decided to provide a plurality of protrusions on the outer surface of the resin tube or the inner surface of the metal tube in order to hold the resin tube at a central position within the metal tube. In that case, the protrusions should be rod-shaped, with the longitudinal direction of the protrusions facing the tube axis direction, and the heights of the protrusions in the tube radial direction should be equal, and the average width of the gap between the resin tube and the metal tube should be 1 The length was increased to 0.8 times. This inventor is
It was confirmed that by doing this, the resin tube could be securely fixed in the center of the metal tube. This invention was made based on such confirmation. This invention uses a long metal tube with a large diameter and a long synthetic resin tube with a small diameter that can be inserted into the long metal tube, and reduces the gap formed between the metal tube and the resin tube to zero.
．． A small width of 2 mm to 2 mm, a plurality of rod-shaped protrusions are formed on the inner surface of the metal tube or the outer surface of the synthetic resin tube, and the protrusions are made of the same material as the resin tube or a harder material,
The longitudinal direction of the protrusion should face the tube axis direction, the height of the protrusion should be equal to 1 to 0.8 times the gap width between the metal tube and the resin tube, and the protrusion should be placed on the inner surface of the metal tube or the outer surface of the resin tube. Apply foaming adhesive to the tube, insert the resin tube into the metal tube,
The present invention relates to a method of manufacturing a synthetic resin-lined metal tube, which is characterized by heating the metal tube to foam and harden the adhesive. The method of this invention will be explained as follows based on the drawings.

FIG. 1 is a cutaway perspective view schematically showing an embodiment of the method of the present invention. FIGS. 2 and 3 are partially enlarged views of the protrusions formed by the method of this invention. FIG. 4 is a partially cutaway cross-sectional view of a tube manufactured by the method of the present invention. In FIG. 1, 1 is a steel pipe, 2 is a hard vinyl chloride pipe, 3 is a protrusion, 4 is an adhesive jet nozzle, 5 is a strut that supports the nozzle 4, and 6 is a coating layer of foamable adhesive. In FIG. 1, four rod-shaped protrusions 3 are attached at equal intervals on the outer surface of the resin tube 2, with their longitudinal direction facing the tube axis direction of the resin tube 2. As shown in FIG.

The protrusion 3 is integrally made of the same material as the resin pipe 2.
The cross-sectional shape may be any shape, but a chevron shape with a tapered tip is preferable. The height h of the peak is desirably about 1 to 0.8 times the gap width (R-r), where the inner diameter of the metal tube 1 is 2R and the outer diameter of the resin tube 2 is 2r. While rotating the synthetic resin tube 2, a foaming adhesive 6 is applied onto the outer surface of the tube. During application, the adhesive is ejected from the ejection nozzle 4. After applying the adhesive in this manner, the resin tube 2 is inserted into the metal tube 1. During insertion, the tip of the protrusion 3 may collide with the inner surface of the metal tube 1, making it difficult to advance, but if you apply a little force, the tip of the protrusion will be deformed or cut by the metal tube 1, so the resin tube 2
can be pushed into the metal tube 1. When pushed in in this manner, the resin tube 2 is supported by the four rod-shaped protrusions 3 of equal height and is fixed at the center position within the metal tube 1. Next, details of this invention method will be explained step by step. In this invention, a large-diameter long metal tube and a small-diameter long synthetic resin tube that can be inserted into the large-diameter long metal tube are used. Here, the term "long" refers to a tube with a length of 1 m or more, usually several meters to a few meters long. In this case, the diameter of the tube is 50 mm or more, usually about 100 mm to 500 mm. When a synthetic resin tube is inserted into a metal tube, an extremely small gap exists between the two tubes. The extent of the small gap width is about 0.2 mm to 2 mm. The size of this gap is a value expressed as an average value. As mentioned above, this gap width is determined by R
It is a value represented by -r. This method uses a foamable adhesive.

This adhesive may be solid or liquid at room temperature, but liquid is preferred. If it is in solid form, it is applied by dissolving it in a solvent or dispersing it in a non-solvent. As the adhesive, it is preferable to use a resin that undergoes a chemical reaction after application to form network-like molecules, particularly a urethane-based, epoxy-based, or polyester-based resin-forming composition. In order to impart foamability to the adhesive, hydrocarbons such as freon, hexane, heptane, or water, etc. are added as a foaming agent to the adhesive. In this method, a foam adhesive is applied to the inner surface of a metal tube or the outer surface of a synthetic resin tube.

When applying, the coating is applied thinly so that the coating thickness is 10 to 90% of the average width of the gap between the two tubes. In addition, considering the foaming ability of the adhesive, the thickness of the coating should be determined so that when the adhesive fills the gap, there is still sufficient foaming capacity. Adjust the coating thickness so that it is less than half the volume.
It is desirable that the coating be uniform both in the tube axis direction and in the circumferential direction. In the method of this invention, protrusions are formed on the outer surface of a synthetic resin tube or on the inner surface of a metal tube. This protrusion may be made of the same material as each tube and may be integral with each tube. In addition, the protrusion is
Each tube may be made of a different material, and the material may be harder than the resin constituting the resin tube. The protrusion has a rod shape and is attached on each tube or between the tubes so that its longitudinal direction extends in the tube axis direction of each tube. Although the protrusion may be cut out in the middle of the tube axis, it is desirable that the protrusion exists continuously from tube end to tube end. It is necessary that a plurality of protrusions be provided in the circumferential direction of the tube, and it is desirable that the protrusions be provided at equal intervals. There are no particular restrictions on the cross-sectional shape of the protrusion.

FIG. 2 shows a state in which six protrusions 3 having an isosceles triangular cross-sectional shape are attached to the outer surface of the resin pipe 2 at equal intervals. FIG. 3 shows a state in which four protrusions 3 each having a semicircular cross-sectional shape are attached at equal intervals on the inner surface of the metal tube 1. As for the cross-sectional shape of the protrusion, it is preferable that the tip of the protrusion is tapered. Regarding the size of the cross section of the protrusion, when the protrusion 3 is integral with the tube as shown in FIGS. 2 and 3, the length a along the circumferential surface of the tube is It must not be large. Length a is metal tube 1
It is desirable that the width is approximately half to twice the average width C of the gap between the resin pipe 2 and the resin pipe 2. Further, the length from the tip of the protrusion 3 to the bottom surface, that is, the height h of the protrusion 3 is required to be 1 to 0.8 times the average width C. Further, the height h of all the protrusions 3 of one tube needs to be equal.
As shown in FIG. 4, when the protrusion 3 is made of a harder material than the resin tube 2 and a different material from the metal tube 1, and is in contact with either tube, the protrusion 3 It is preferable that the cross section is approximately circular and its diameter is 1 to 0.8 times the average width C. It is necessary to increase the number of protrusions attached to one tube as the diameter of the tube becomes larger, and as the gap width becomes larger, it is necessary to increase the number of protrusions. Furthermore, as the viscosity of the foamable adhesive decreases, the number of protrusions needs to increase. Immediately after applying the foaming adhesive to at least one of the tubes, the resin tube is inserted into the metal tube. At this time, a plurality of protrusions are formed on the surface of one tube, and the height h of the protrusions is set to 1 to 0.8 of the average width C in the gap between the metal tube and the resin tube. The tip ends of the tube forcefully come into contact with each other only in areas with large distortions or errors on the inner surface of the metal tube or the outer surface of the resin tube. As a result, the resin tube is reliably held at a central position within the metal tube. After insertion, the metal tube is heated to cause the adhesive to foam and harden.

It is desirable that the heating be performed so that the inner surface of the metal tube reaches a temperature of 80 to 100°C. Further, it is desirable that the heating be performed as quickly as possible. There are no particular restrictions on the heating method, and various methods such as hot water, steam, hot air, infrared rays, and induction heating can be employed. According to the method of this invention, a long metal tube with a large diameter and a long synthetic resin tube with a small diameter that can be inserted therein are used, and the gap formed between the metal tube and the resin tube is reduced to 0 on average. .2mm to 2n, which is a small width.
A lined tube with a thin foamed adhesive layer can be obtained, and therefore a lined tube with a large capacity and a high quality in which the resin tube is firmly bonded to the metal tube can be obtained.

In addition, since multiple protrusions are attached to the surface soil of one of the pipes, and the height of the protrusions is 1 to 0.8 times the average width of the gap, it is common practice to insert a resin pipe into a metal pipe. can be pushed in easily. In some cases, due to an error or distortion in the tube shape, the tip of the protrusion collides with the tube surface and prevents the tube from being pushed in. However, since one of the tubes is a resin tube, if it is forced in, The resin tube is distorted or deformed, and as a result, the resin tube can be inserted. Further, after being inserted in this manner, the resin tube is held at a central position within the metal tube because the protrusion stretches. This is true even if adhesive is present. In this way, the resin tube is fixed at a central position within the metal tube. According to the method of this invention, a foamable adhesive is applied to the inner surface of a metal tube or the outer surface of a resin tube, and the resin tube is inserted into the metal tube before the adhesive is foamed, so that the adhesive is thinly applied. , and can also be evenly distributed between both tubes.

If the adhesive coating thickness is made smaller than the gap width and the adhesive is foamed in a narrow space that is less than half the volume that will expand due to free foaming, the adhesive will fill the gap well and create a large number of closed cells. It becomes a foam. For this reason, a high-quality lining pipe with a small gap width can be obtained. Furthermore, in the method of this invention, the protrusions are made to penetrate through the resin tube from end to end, adhesive is applied to the surface on which the protrusions are attached, the tube is held horizontally, and the protrusions are placed on the side of the tube axis. If placed in the opposite direction, the protrusion will prevent the adhesive from dripping due to its own weight.

The protrusions therefore also aid in even distribution of adhesive. Next, the details of the method of the present invention will be further explained with reference to Examples.
As an example metal tube, the outer diameter is 110wm and the inner diameter is 106W! 11 Using a steel pipe with a length of 5 m, the outer diameter is 04W as a synthetic resin pipe! ζ
A hard vinyl chloride pipe with an inner diameter of 100111 and a length of 5 m was used.

As a result, when the synthetic resin tube was inserted into the metal tube, there was a gap of 1.0 ml between the two tubes. A stock solution for producing semi-rigid urethane resin was used as the foamable adhesive.

This stock solution had the following composition in parts by weight:
When this stock solution was allowed to foam freely, it expanded to about 30 times its size and became a foam with open cells.

The protrusions were formed on the outer surface of the synthetic resin tube.

When forming the resin tube, three of these protrusions were formed at equal intervals on the outer surface of the tube, and were present so as to penetrate from one end of the tube to the other. Its cross-sectional shape was approximately an equilateral triangle, and its height h was 0.95 times the gap width. The foam adhesive was applied to the inner surface of the metal tube.

When applying, insert the jet nozzle into the metal tube,
This was done by jetting the adhesive from a jet nozzle. After application,
A resin tube with a protrusion was immediately inserted. Insertion was easy and the resin tube was held in the center of the metal tube. After insertion, hot air at 100° C. was blown onto the outer surface of the metal tube to heat the metal tube. As a result, the stock solution rapidly foamed and hardened. In the thus obtained synthetic resin-lined metal tube, the resin tube was located at the center of the metal tube, there was almost no eccentricity, and the resin tube and the metal tube were strongly bonded to each other. Furthermore, even after the tube was repeatedly heated and cooled, the synthetic resin tube showed little shrinkage at the tube end, and was good as a lining tube.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view schematically showing an embodiment of the method of the present invention.

Claims (1)

[Claims] 1 Using a long metal tube with a large diameter and a long synthetic resin tube with a small diameter that can be inserted into the long metal tube, the gap formed between the metal tube and the resin tube is 0.2 mm to 2 mm on average. The width is small, and multiple rod-shaped protrusions are formed on the inner surface of the metal tube or the outer surface of the synthetic resin tube, the protrusions are made of the same material as the resin tube or a harder material, and the longitudinal direction of the protrusions is oriented toward the tube axis. , the height of the protrusion is set to an equal length of 1 to 0.8 times the width of the gap, a foaming adhesive is applied to the inner surface of the metal tube or the outer surface of the resin tube, and the resin tube is inserted into the metal tube, A method for producing a synthetic resin-lined metal tube, which comprises heating the metal tube to foam and harden the adhesive.