JPS5949886B2 - 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.

Conventionally, as a composite pipe, for example, ιL JP-A-50-3587
No. 7 or Japanese Utility Model Application Publication No. 118221/1983, a structure in which a foam layer of synthetic resin is interposed between a metal tube and a synthetic resin tube is known, and in order to manufacture this composite tube, , after inserting the synthetic resin pipe into the metal pipe, between the two pipes,
A method is used in which a liquid material forming a synthetic resin foam is injected, a metal tube is simply heated, and the liquid material is foamed and hardened.

However, with this method, when heated, foaming starts in various places in both tubes, forming air pockets, making it impossible to evenly fill the gap between the two tubes with foam, which makes it difficult to firmly bond the two tubes together. The disadvantage of not being able to do so has disappeared. The present invention was made for the purpose of solving the above-mentioned conventional drawbacks, and the gist thereof is to use an adhesive in which a synthetic resin pipe is inserted into a metal pipe and a foam is hidden between the two pipes. A cold equalization zone forcibly cools the tube body with the adhesive interposed therein so that the tube body is kept at a temperature below the temperature at which the adhesive starts foaming from one part to the other part, and the same adhesive immediately foams. A method for manufacturing a synthetic resin-lined metal tube is characterized in that the tube body is forcibly heated to a temperature at which the tube body is heated through successive heating zones, and the adhesive is foamed and cured.

As the metal tube used in the present invention, what is generally called a metal tube such as a steel tube, a stainless steel tube, a copper tube, etc. can be used.
Those having a length of 1 m or more, usually from several meters to several tens of 5 m, and a diameter of 50 m or more, usually from 100 to 1000 m, are preferably used.

Examples of synthetic resin pipes used in the present invention include vinyl chloride resin pipes, polyethylene V pipes, polypropyne V pipes,
A polyamide tube or the like is used, and its outer diameter is such that when inserted into the metal tube, the gap between it and the inner peripheral surface of the metal tube is 0.3 to 3.0.
U is preferably used.

In the present invention, the adhesive may be either liquid or solid at room temperature, but liquid is preferred.

If it is in solid form, it is used by dissolving it in a solvent or dispersing it in a non-solvent. Specifically, urethane-based, epoxy-based,
Unsaturated polyester resins are preferred. In order to impart foaming properties to these resins, hydrocarbons such as hydrocarbons, hexane, heptane, water, etc. are included as foaming agents.

The present invention will be explained below by way of examples with reference to the drawings.

1 is a synthetic resin pipe, and 4 is a metal pipe.

Adhesive 3 is applied to the outer surface of the synthetic resin pipe 1 using a spray gun 2.
and insert it into the metal tube 4. The glue may be applied to the inner surface of the metal tube. When applying the adhesive 3, in order to leave room for foaming, the coating thickness should be 10 to 90% of the average gap between the plastic tube 1 and the metal tube 4, and the volume of the gap should be half of the volume when free foaming occurs. Adjust to keep it below. After applying the adhesive 3, it is desirable to rotate at least one of the two tubes to prevent the adhesive 3 from sagging due to its own weight when inserting the synthetic resin tube 1 into the metal tube 4. The process so far is short, usually 1
3 minutes, but Adhesive 3 is formulated so that it does not start foaming at room temperature during that time. Next, the synthetic resin tube 1 is inserted into the metal tube 4 and the tube body 5 is appropriately covered with a cap at one end. Starting from one end, the tube passes sequentially through a through hole in a box provided in succession with the cooling zone 6 and the heating zone 8. In the cooling zone 6, a cooling liquid 10 such as cold water is injected from a ring nozzle 7, and in the heating zone 8, hot water 11 is injected from a ring nozzle. The heating method in the heating zone 8 is not limited to hot water, and various methods such as hot air, steam, infrared lamps, and induction heating can be used, but hot water is suitable for rapid heating. The heating in the heating zone 8 is adjusted so that the adhesive 3 immediately begins to foam, ie the inner surface of the metal tube reaches a temperature of 80-100°C. Further, the cooling in the cooling zone 6 is controlled so that the temperature of the adhesive 3 is kept below the temperature at which it starts to foam, that is, so that the inner surface of the metal tube is kept at a temperature below 40°C. When the tube 5 sequentially passes through both zones, the heat applied to the portion of the tube 5 that is passing through the heating zone 8 is not transferred to the portion of the tube 5 that is passing through the cooling zone 6. Foaming of the adhesive 3 after the heating zone 8 is suppressed, and then within the heating zone 8, the adhesive 3 is foamed and hardened sequentially from one end through which the tube 5 passes, so that air pockets are not formed between the two tubes. A synthetic resin lined metal tube is formed which is filled with foam and has both tubes firmly bonded together.

In the above-mentioned embodiment, the pipe body 5 is passed through the cooling zone 6 and the heating zone 8 from one end thereof, but the pipe body 5 is not limited to this, and the pipe body 5 may be cooled from the middle part toward both ends. The heating zone may be moved.

Furthermore, as in the embodiment described above, if the synthetic resin tube 1 is inserted into the metal tube 4 after applying the adhesive 3 to the outer surface of the synthetic resin 1 or the inner surface of the metal tube 4, both This is preferable because the adhesive 3 can be distributed uniformly in the pipe, but the invention is not limited to this, and when both pipes are short, after inserting the synthetic resin pipe into the metal pipe, An adhesive with latent foaming properties may be injected during this period.

As described above, the method for manufacturing a synthetic resin-lined metal pipe of the present invention involves inserting a synthetic resin pipe into a metal pipe, and forming a part of the pipe body with an adhesive interposed between the two pipes with a foam latent therein. a cooling zone that forcibly cools the tube body so that the tube body is maintained at a temperature below the temperature at which the adhesive b starts to bubble from the adhesive b to other parts;
The tube is forcibly heated to a temperature at which the adhesive immediately begins to foam. The applied heat is not transmitted to the part of the tube that is passing through the cooling zone, and the foaming of the adhesive is suppressed until it has passed through the cooling zone, and the adhesive foams and hardens only in the heating zone. The air between the two tubes is sequentially forced toward the cooling zone side and expelled backwards, and the foam is filled to prevent air pockets from forming between the two tubes, making it possible to firmly bond the two tubes together. . Next, the present invention will be explained in detail by giving more specific examples.

Example A steel pipe with an outer diameter of 114.3 mm, an inner diameter of 105.3 mm, and a length of 5 m was used as the metal pipe, and as a synthetic resin pipe, an outer diameter of 10 mm was used.
A hard vinyl chloride pipe with a diameter of 3.3 m, an inner diameter of 95.3 m, and a length of 5 m was used.

A semi-rigid urethane stock solution was used as the adhesive.

This stock solution had the following composition (parts by weight). When this stock solution of triol (molecular weight 3000, OH value 56) was allowed to foam freely, it foamed to about 30 times its original size, producing an open-cell foam.

While rotating the synthetic resin tube, the stock solution was uniformly applied to the outer surface of the synthetic resin tube to a thickness of 0.5 mm, and the tube was moved forward and inserted into a metal tube rotating at the same speed. Cover one end of this pipe with a cap and make a length of 300T from that end.
n cooling zone, 250cm long heating zone 1m/
It passed at a speed of 1 minute.

18℃ cold water in the cooling zone, 100℃ in the heating zone
℃ hot water was injected directly into the tube. As a result, the stock solution rapidly foamed and hardened. The synthetic resin-lined metal tube thus obtained was cut into 245 pieces of 2CfL each, leaving 5 (1771 pieces) at each end, and the adhesive layer on the cut surfaces was observed and the adhesive strength was measured (.) Punching using WWAKll6-1927. test).

As a result, observation of the adhesive layer on the cut surface revealed that the gap between the synthetic resin pipe and the metal tube was filled with the adhesive foam layer, and there were no voids caused by air pockets.

In addition, the average punching strength of 245 pieces was 14.2 kg/(11
F! 2. The standard deviation was 1.2, indicating strong adhesive strength with no variation. For comparison purposes, samples of lining pipes were prepared in the same manner as in the examples except that during the above implementation, the cold water in the cooling zone was not injected, and evaluations and evaluations were conducted in the same manner as in the examples.

As a result, air gaps were found in 28 out of 245 pieces, and the punching strength was on average 8.7 kgAm1 with a standard deviation of 3.1, and the adhesion was not good.

As mentioned above, in the synthetic resin lined metal pipe obtained by the present invention, there was no air pocket between the synthetic resin pipe and the metal pipe, and both pipes were strongly bonded.

[Brief explanation of the drawing]

FIG. 1 is a front view illustrating the first half of the process in the embodiment of the present invention, and FIG. 2 is a partially longitudinal front view illustrating the second half of the process in the embodiment of the present invention. Explanation of symbols 1...Synthetic resin pipe, 3...
・Adhesive, 4... Metal tube, 6... Cooling zone, 8... Heating zone.

Claims (1)

[Claims] 1 A pipe body in which a synthetic resin pipe is inserted into a metal pipe and a potentially foamable adhesive is interposed between the two pipes is maintained at a temperature below the temperature at which the adhesive starts foaming from one part to the other part. The adhesive is passed through a cooling zone where the pipe is forcibly cooled so as to cause the adhesive to foam and harden through a heating zone where the pipe is forcibly heated to a temperature at which the adhesive immediately begins to foam. A manufacturing method for synthetic resin-lined metal pipes.