JP2001287004A - Composite tube and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite tube having good manufacturing efficiency without needing a mold, and a manufacturing method therefor. SOLUTION: On the inner surface of a steel tube 5 where a thermal-sprayed film 3 of a self-fluxing alloy is formed, a stainless steel tube 7 formed with a centrifugal casting is provided. Instead of the steel tube, a cast iron tube can be used, and instead of the stainless steel tube, a nickel alloy, titanium or titanium alloy can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite pipe and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, cast iron pipes are most widely used as water distribution pipes. However, there is also a problem of deterioration due to corrosion or casting defects. Therefore, MSFN is applied to the outer periphery of a stainless steel pipe (SUS304TB) having corrosion resistance.
A method is known in which a self-fluxing alloy equivalent to i3 is sprayed, and this tube is used as a core, and then mounted on a sand mold, and then cast iron (FCD400) is cast. According to this method, the coating on the outer periphery of the stainless steel pipe is completely melted by the heat of the molten cast iron,
A composite steel pipe can be manufactured in which the inner surface is diluted and diffused and the interface exhibits a continuous phase without a film diffusion layer. The inner surface is stainless steel and the outer surface is cast iron.

[0003]

However, since the above method requires an outer mold such as a sand mold, there is a problem that the manufacturing efficiency is low and the manufacturing cost is high. The present invention has been made to solve such a problem,
It is an object of the present invention to provide a composite pipe which does not require a mold and has high production efficiency and a method for producing the same.

[0004]

The composite pipe according to the present invention comprises:
It has an inner layer of a corrosion-resistant metal formed by centrifugal casting on the inner surface of a tube on which a spray coating of a self-fluxing alloy is formed.

[0005] Further, the pipe is a steel pipe.

Further, the pipe is a cast iron pipe.

Further, the self-fluxing alloy is a Ni-based self-fluxing alloy.

[0008] The corrosion-resistant metal is stainless steel.

In the method for manufacturing a composite pipe according to the present invention, a step of forming a spray coating of a self-fluxing alloy on the inner surface of the pipe, and forming an inner layer of a corrosion-resistant metal by centrifugal casting on the inner surface of the spray coating formed by the step. And a step of performing

[0010]

FIG. 1 is a sectional view of a composite pipe according to an embodiment of the present invention. Composite pipe 1 according to the present embodiment
As shown in FIG. 1, a stainless steel pipe 7 formed by centrifugal casting is formed on the inner surface of a steel pipe 5 on which a spray coating 3 of a self-fluxing alloy is formed.

FIGS. 2 to 5 are explanatory views of a manufacturing method according to an embodiment of the present invention. Hereinafter, the manufacturing method according to the present embodiment will be described with reference to FIGS. As shown in FIG. 2, a steel pipe 5 serving as an outer pipe is set on a rotating roller 9 for centrifugal casting. At this time, the steel pipe 5 is rotatably held by an unillustrated stopper to prevent the steel pipe 5 from being displaced by the rotation. In this state, as shown in FIG. 3, the spray nozzle 11 of the thermal spraying device (not shown) is inserted into the steel pipe 5, and the self-fluxing alloy is sprayed on the inner surface of the steel pipe 5 while rotating the steel pipe 5 by the rotating roller 9. Thus, a thermal spray coating 3 of a self-fluxing alloy is formed. In the present embodiment, a Ni-based self-fluxing alloy suitable for thermal spraying on steel and stainless steel is used as the self-fluxing alloy.

After forming the thermal spray coating 3 on the inner surface of the steel pipe 5,
As shown in FIG. 4, each of the lid members 13 and 13 is provided so that the molten metal does not leak from the casting side and the end opposite to the casting side.
15 is welded. The casting-side lid member 13 is provided with an insertion hole 13a into which the spout 17 for molten metal can be inserted.

Next, the steel pipe 5 is rotated at a high speed by the rotating roller 9, and the molten metal pouring port 17 is inserted into the insertion hole 13 a of the lid member 13, and the molten stainless steel is poured into the steel pipe 5 from the pouring port 17. Hot water. The pouring port 17 is in communication with a truck 21 that stores the molten metal and is movable on the rails 19. By moving the truck 21, the molten metal can be poured over the entire length of the steel pipe 5.

The molten metal that has dropped on the inner surface of the steel pipe 5 by the pouring is pressed against the inner wall of the steel pipe 5 by the action of centrifugal force, and as shown in FIG. 5, a stainless steel pipe 7 that gradually becomes the inner pipe is formed. At this time, the thermal spray coating 3 is completely melted by the heat of the molten metal, diluted and diffused, and the pipe interface between the steel pipe 5 and the stainless steel pipe 7 becomes a continuous phase without a coating diffusion layer. As a result, the boundary between the steel pipe 5 and the stainless steel pipe 7 is in a firmly connected state.

As described above, according to the present embodiment, the joining strength between the steel pipe 5 and the stainless steel pipe 7 can be increased, and a sand mold is not required, thereby increasing the production efficiency. Further, in the above embodiment, since the steel pipe is used as the outer pipe, the pipeline can be efficiently constructed by welding, and the earthquake resistance is excellent.
Further, since a steel pipe is used for the outer pipe and a stainless steel pipe is used for the inner pipe, only one kind of welding material is required for welding between the pipes, and welding can be easily performed.

In the above embodiment, an example is shown in which stainless steel is used for the inner tube. However, as the material having corrosion resistance, for example, a nickel alloy, titanium, or a titanium alloy may be used. Further, although the example of the outer tube is a steel tube, a cast iron tube may be used. In this case, various joints are used for connecting the pipes.

[0017]

According to the present invention, since the inner surface of the corrosion-resistant metal formed by centrifugal force casting is formed on the inner surface of the tube on which the spray coating of the self-fluxing alloy is formed, the joining strength between the tube and the inner tube of the corrosion-resistant metal can be increased. Can be. In addition, the need for a sand mold is eliminated, the production efficiency is increased, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a manufacturing process (part 1) of the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a manufacturing process (part 2) according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a manufacturing process (part 3) according to the embodiment of the present invention.

FIG. 5 is an explanatory view of a manufacturing step (part 4) of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Composite pipe 3 Thermal spray coating 5 Steel pipe 7 Stainless steel pipe 9 Rotary roller 11 Thermal spray nozzle 13 Pouring port

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C23C 4/16 C23C 4/16 F16L 9/02 F16L 9/02 F term (Reference) 3H111 AA01 BA02 BA03 CA53 CB08 CB22 DA08 DB03 EA07 EA16 4K031 AA01 AA05 AB09 CB30 EA01 EA03 EA05

Claims (6)

[Claims] 1. A composite pipe having a corrosion-resistant metal inner layer formed by centrifugal casting on an inner surface of a pipe on which a spray coating of a self-fluxing alloy is formed. 2. The composite pipe according to claim 1, wherein said pipe is a steel pipe. 3. The composite pipe according to claim 1, wherein said pipe is a cast iron pipe. 4. The composite pipe according to claim 1, wherein the self-fluxing alloy is a Ni-based self-fluxing alloy. 5. The composite pipe according to claim 1, wherein the corrosion-resistant metal is stainless steel. 6. A step of forming a sprayed coating of a self-fluxing alloy on the inner surface of a pipe, and a step of forming an inner layer of a corrosion-resistant metal by centrifugal casting on the inner surface of the sprayed coating formed in the step. A method of manufacturing a composite pipe.