KR100375772B1 - The internal coating method of a iron and The iron pipe which is internal-coated by this method - Google Patents

Abstract

The present invention relates to an iron pipe that is to prevent corrosion by coating a synthetic resin film on the inner circumferential surface of a cast iron pipe or steel pipe used as a water pipe or sewage pipe, that is, a method for producing cast iron pipes and steel pipes and the synthetic resin coated steel pipes produced thereby.

Water pipes or sewer pipes are divided into two categories. One example is a steel pipe formed by rolling a steel sheet sheet and integrally forming a contact portion by welding, and a cast iron pipe made by pouring molten metal into a centrifugal casting mold.

The steel pipe is oxidized and corroded as it is used, and the present invention is conceived in consideration of deterioration of tap water by contaminating the inside of the pipe with foreign matters. After heating to a temperature, a synthetic resin powder or a synthetic resin solution is administered to the inner diameter, and when it is rotated, the synthetic resin administered to the pipe inner diameter by centrifugal force is attached to the inner circumferential surface of the steel pipe with an even thickness in the liquid phase.

Description

The internal coating method of a iron and The iron pipe which is internal-coated by this method}

The present invention relates to a method for producing cast iron pipes and steel pipes to prevent corrosion by coating a synthetic resin film on the inner circumferential surface of cast iron pipes or steel pipes used as water pipes or sewer pipes, and the anti-corrosion cast iron pipes and steel pipes produced thereby.

Steel pipes used as water pipes or sewer pipes can be classified into two types.

One can be distinguished from cast iron pipe which is manufactured by centrifugal rotational force by pouring molten casting into a centrifugal casting mold, and the other is a steel pipe which is formed by welding a part to be contacted while bending a sheet iron sheet spirally.

The cast iron pipe manufactured by the centrifugal casting method made by pouring the molten casting into a centrifugal casting mold has a rough surface while cooling, and when the temperature of the molten water is not constant or the cooling temperature is not uniform, the tissue becomes hard to be dense. It can be seen that a fine hole (pin hole) is generated, and in the steel pipe formed by welding a portion of the steel sheet sheet which is bent in a spiral shape, a weld line is formed on the inner circumferential surface and the outer circumferential surface.

Since cast iron pipes cannot form large diameter pipes with a diameter of 1500-2000 mm, large diameter pipes with a diameter of 1500-2000 mm generally use steel pipes. In the conventional cast iron pipe to prevent corrosion it can be seen that the coating on the inner, outer circumferential surface (coaltar), or to form a cement mortar lining on the inner circumferential surface.

In this way, when the coal tar or cement mortar deposited on the inner circumferential surface of the cast iron pipe is deposited on the inner circumferential surface of the cast iron pipe, it prevents the oxidation effect of the cast iron pipe and prevents pin holes formed on the surface to protect the inner circumferential surface of the cast iron pipe. However, it has been recently discovered that when coal-coated or cement mortar-lined cast iron pipes are used as water pipes, coal-talle or cement slowly dissolves in tap water and acts as a toxic substance harmful to the human body.

Thus, in order to prevent the oxidation of cast iron pipes, in consideration of the harmfulness of the molten lining of the cast iron pipes or cement mortar lining, a separate synthetic resin pipe is inserted into the inner diameter of the steel pipe to prevent corrosion. The manufacturing method of 'can be seen.

The patent No. 232902 is to insert a synthetic resin pipe into the inner diameter of the steel pipe to match the outer peripheral surface of the synthetic resin pipe and the inner peripheral surface of the steel pipe to prevent corrosion by oxidation of the steel pipe.

However, the present invention, unlike the pre-registered patent for inserting the synthetic resin pipe into the inner diameter of the steel pipe and prevents the reinforcement and oxidation of the steel pipe is formed on the inner circumferential surface of the cast iron pipe by coating the inner circumferential surface of the cast iron pipe formed by centrifugal casting with synthetic resin powder or synthetic resin solution It fills the pinhole, which is a minute hole, and prevents the corrosion caused by the oxidation of the cast iron pipe, thereby providing a water supply pipe that transports the tap water hygienically.

The present invention enables the present invention to be easily applied to not only cast iron pipes manufactured by centrifugal casting, but also steel pipes in which spirally bent steel sheet sheets are formed integrally by welding.

An object of the present invention is to provide a cast iron pipe or steel pipe to form a synthetic resin film on the inner circumferential surface of the cast iron pipe or steel pipe to prevent corrosion caused by oxidation to supply tap water more cleanly and sanitarily.

Water pipes buried in the ground should have robustness that is not easily broken or broken by earth pressure or other loads and should not be easily oxidized and corroded. The rigidity of the water pipe is maintained in proportion to its thickness, but in order to prevent corrosion by oxidation, a non-oxidized material must be inserted into the inner diameter of the tube or coated on the inner diameter of the tube.

In order to prevent the oxidation of cast iron pipes, the anti-corrosion treatment method used on the inner and outer circumferential surfaces of the pipe is coated on the inner circumferential surface or outer circumference of the cast iron pipe by coating coal byproduct of crude oil, by inserting cement lining based on cement, or by adding cement mortar Although the film was formed, cement or coaltal emits harmful substances to the human body, so it is not suitable as a coating for preventing corrosion of water pipes for supplying drinking water.

In view of the above, the present invention is made by dissolving and depositing a synthetic resin material which is not harmful to the human body in the cast iron pipe or the inner circumferential surface of the steel pipe. By rotating the steel pipe, the resin powder is deposited on the inner circumferential surface of the heated tube by the centrifugal force generated by the rotation.

1-A cross-sectional view of a cast iron pipe made according to the present invention.

2 is a schematic cross-sectional view of a centrifugal casting machine for producing a cast iron pipe.

3 is a schematic cross-sectional view showing implementation of the present invention during the manufacturing process of a conventional cast iron pipe.

Figure 4-A-A cross sectional view of Figure 3 showing an embodiment of the present invention.

FIG. 5-A-A cross sectional view of FIG. 3 showing an embodiment of the present invention; FIG.

6 is a schematic cross-sectional view showing heating of a cast iron pipe in a heating furnace according to the present invention.

7 is a schematic cross-sectional view showing a process of rotating a heated cast iron pipe.

8-Cross-sectional view taken along line B-B in FIG. 7 as an embodiment of the present invention.

FIG. 9-Section B-B of FIG. 7 as an embodiment of the present invention. FIG.

The manufacturing process of the present invention is described as follows.

The present invention is to coat the synthetic resin on the inner circumferential surface of the steel pipe, that is, cast iron pipe or steel pipe, first remove foreign substances on the inner circumferential surface of the cast iron pipe 11, then put it in the heating furnace 42 and heated to 300-350 ℃, cast iron pipe (11) is mounted on the rotary roller 41, while rotating the cast iron pipe (11) while the synthetic resin powder 21 is introduced into the powder feed pipe 31 into the inner diameter of the cast iron pipe (11) inner peripheral surface It is dissolved in and deposited.

When rotating the heated cast iron pipe 11 while administering the synthetic resin powder 21 inside thereof, the fine resin hole formed by the centrifugal force on the inner circumferential surface of the cast iron pipe 11 by the centrifugal force to adhere to the inner circumferential surface of the cast iron pipe 11 Synthetic resin solution evenly penetrates the grooves or grooves to block fine holes or grooves, and because the centrifugal force is generated in the inner diameter of the cast iron pipe 11 that is rotated, the synthetic resin solution in the molten state is deposited on the inner circumferential surface of the cast iron pipe 11 at an even thickness. will be.

Putting the cast iron pipe 11 in the heating furnace 42 and heating it to a predetermined temperature, that is, the melting temperature of the synthetic resin corresponds to a method of coating the synthetic resin powder or the synthetic resin solution on the inner circumferential surface of the already completed cast iron pipe, the present invention cast iron pipe It can be applied during the manufacturing process.

In general, cast iron pipe is poured molten molten iron in the casting mold 12 mounted on the centrifugal casting machine to form a cast iron tube. At this time, the temperature of the molten iron is cast into a centrifugal casting machine to form a cast iron tube. After cooling to, it is removed from the casting mold 12. When the temperature of the cast iron pipe during the cooling process corresponds to 250-300 ° C., the melting temperature of the resin powder 21, the synthetic resin material through the powder supply pipe 31 in the inner diameter of the cast iron pipe The present invention can be carried out during the manufacturing process of the cast iron pipe by administering the powder 21 or supplying the synthetic resin solution through the nozzle.

The present invention will be described in more detail as follows.

In the previously manufactured steel pipe or cast iron pipe 11, after removing the foreign matter of the inner diameter, and put it in a heating furnace 42 provided with heating means to heat the steel pipe or cast iron pipe 11 to 250-300 ℃, and then the rotary roller ( 41), the U-shaped powder supply pipe 31 is pushed into one side of the opening, and then the powder supply pipe 31 is rotated 180 ° so that the synthetic resin powder 21 contained therein is cast iron pipe 11 inside diameter. Synthetic resin powder 21 is melted in the solution 22 state on the inner circumferential wall of the cast iron pipe 11 by the centrifugal force of the cast iron pipe 11 that is rotated when poured into, and is deposited to a uniform thickness by the centrifugal force. .

In the above, the synthetic resin solution may be supplied to the inner circumferential surface of the cast iron pipe 11 by using a nozzle that reciprocates the synthetic resin solution in the molten state from side to side instead of the synthetic resin powder 21.

The heating temperature of the cast iron pipe is to take into account the temperature of the cast iron pipe 11 is mounted on the rotary roller 41, and then rotated, and corresponds to the temperature at which the synthetic resin powder can be sufficiently melted, the melting temperature of the synthetic resin powder used and The heating temperature of the cast iron pipe 11 is increased or decreased depending on the amount.

In addition, the thickness of the synthetic resin solution 22 to be deposited can be arbitrarily calculated as the thickness of the synthetic resin powder 21 is small and large.

In bending the steel sheet and coating the resin on the inner diameter of the cast steel pipe manufactured by welding, the cast steel pipe is heated to 250-300 ℃, which is the temperature at which the synthetic resin is melted, and then the cast steel pipe is rotated through a rotary roller to generate centrifugal force and centrifugal force. By the synthetic resin powder is to be deposited on the inner peripheral surface of the pipe.

The synthetic resin is to be used in the form of a powder, the material can be used almost any synthetic resin, such as synthetic resin material that melts when applying heat such as PE, PP, PVC, FRP, or a mixture of 2-3 kinds Will be.

The molten deposition of synthetic resin material on the inner diameter of cast iron pipe or steel pipe prevents corrosion caused by oxidation of cast iron pipe or steel pipe, which prolongs the life of water pipe, and is caused by minute holes generated during casting of cast iron pipe and thermal deformation during cooling. The inner surface of the tube is smoothed by filling the groove of the surface to prevent the parasitic of aquatic organisms such as shellfish, aquatic plants, and earthworms on the inner surface of the tube. You can get the effect of preventing it.

As such, the synthetic resin coating film in which the synthetic resin powder or the synthetic resin solution is deposited on the inner circumferential surface of the steel pipe or cast iron pipe forms another synthetic resin pipe on the inner wall of the steel pipe or the cast iron pipe when a certain thickness is reached. Even if the steel pipe is broken or cracked, the inner synthetic resin pipe is not easily broken at the same time, and thus, the effect of preventing the leak of the pipe is expected.

The present invention reinforces the steel pipe or cast iron pipe, smooth the inside of the pipe to suppress foreign matter adhesion and scale generation, in particular, it is a very useful invention that can supply clean tap water without contamination.

Claims (3)

In a cast iron pipe made of molten molten metal by centrifugal casting, foreign substances of the inner diameter of the cast iron pipe 11 are removed and cleaned, and then charged into a heating furnace 42 equipped with a heating means, which is heated to 250-300 ° C. After the mounting, it is mounted on the rotary roller 41, the synthetic resin powder 21 is put in the inner diameter thereof, and the cast iron pipe 11 is rotated so that the synthetic resin powder 21 is deposited on the inner circumferential surface of the cast iron pipe 11 by centrifugal force and simultaneously melted. A method for producing a synthetic resin coated iron pipe, characterized in that the film (22) is formed. The method of claim 1, wherein when the temperature of the cast iron pipe is cooled to 250-300 ℃ when manufacturing the cast iron pipe produced by centrifugal casting, the synthetic resin powder or synthetic resin powder 21 is put into the inner diameter of the cast iron pipe to rotate the cast iron pipe. Method for producing a synthetic resin coated iron pipe, characterized in that the synthetic resin film 22 is formed on the inner peripheral surface of the cast iron pipe. After the cast iron pipe 11 is heated to the synthetic resin dissolution temperature, the synthetic resin powder 21 is administered to the inner diameter while rotating it, and the synthetic resin powder is melted so that the synthetic resin film 22 is formed on the inner circumferential surface of the cast iron pipe 11. Coated iron pipe.