JPH027704B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for painting the inner surface of fluid conduits, such as water pipes, and to an apparatus used to carry out the method.

(Conventional Example) In addition to conventional ductile cast iron pipes, welded steel pipes are now being used as water supply pipes.

To connect these steel pipes, as shown in Figure 4, the end surfaces of conduits a and b are brought together and welded. As a result, the tar epoxy coating d painted on the inner surface of the pipe was burned away, and the base material e of the steel pipe
The problem arises that the image is exposed. Therefore, after such welding work, it has been common practice to manually paint the inner surface of the pipe in order to prevent rust from forming on the inner surface of the pipe.

If the diameter of the pipe is large, a worker can enter the pipe and paint the pipe, but for small-diameter pipes with an inner diameter of 600 mm or less, there is no suitable means for painting the inner surface, such as a brush attached to the tip of a stick. Therefore, measures such as inserting it into the conduit are taken, which is time-consuming. Coating the inside surface of tubing systems with bends is even more difficult.

Note that if the inner surface coating of such pipes is omitted, rust will occur where the base material is exposed, resulting in the formation of red water, and the cross-sectional view will be reduced due to rust, making it difficult to obtain the planned flow rate. Problems may arise, such as not being able to do so.

(Object of the Invention) The present invention aims to provide a method for coating the inner surface of a conduit that can easily mechanically coat the inner surface of a small-diameter conduit, and an apparatus for coating the inner surface of a conduit used in this method. It is something to do.

(Structure of the Invention) The method for painting the inner surface of a conduit according to the present invention includes a sliding stopper in which a nozzle head is protruded from the front end surface of a cylindrical main body, and a traction cord and a hose for pumping paint are connected to the rear end surface. is slidably inserted into the conduit in an almost airtight state, and air pressure is applied to the rear end side of the sliding plug to move the sliding plug to the coating start position in the conduit. By pulling the reference cord from the entrance side of the conduit, the sliding plug is retracted and paint is sprayed from the nozzle head to form a coating film on the inner circumferential surface of the conduit. be.

Further, the inner surface coating apparatus for a conduit according to the present invention is an apparatus used in the above-mentioned inner surface coating method, and includes:
A sliding plug body is provided with a nozzle head in the center of the front end surface of a cylindrical main body, and an elastic body is fitted on the outer circumferential surface of the body so as to be able to make almost airtight sliding contact with the inner circumferential surface of the conduit; A traction cable whose tip end is connected to the rear end surface and whose base end is wound around a winding device; and a paint pumping cable whose tip end is connected to the nozzle head and whose base end is connected to a coating machine. It is equipped with a hose.

(Example) Hereinafter, an embodiment of the inner surface coating apparatus according to the present invention will be explained based on FIG. This will be explained in detail based on the following.

Reference numeral 1 shown in FIG. 1 is a substantially cylindrical sliding stopper, which is a main component of the inner surface coating device 2. As shown in FIG.

As shown in FIG. 2, this movable nozzle 1 has a pair of front and rear end plates 3a, 3 facing each other with a gap between them.
b, and a cylinder 3c held between these end faces, and a material having flexibility and elasticity, such as polyurethane foam, fitted around the outer periphery of the cylinder 3c of the main body 3. an elastic body 4;
It consists of a nozzle pipe 5 that passes through the center of each end plate 3a, 3b of the main body 3 and is fixed integrally therewith.

The tip of this nozzle pipe 5 is connected to the front end plate 3a.
A nozzle head 5a projecting from the nozzle tube 5 and for spraying paint is attached to this nozzle pipe 5.

A proximal end of the nozzle pipe 5 protruding from the rear end plate 3b is connected to a distal end of a hose 6 for pumping paint.

The base end of the hose 6 is connected to the discharge side of a coating machine 7 by a motor.

Reference numeral 8 denotes a traction cable, that is, a wire, whose distal ends 8a, 8a are bifurcated, and each passes through the end plates 3a, 3b and is connected to the main body 3, and its proximal end The section is wound onto a drum 10 of a cable winding device, ie a manual or electric winch 9.

A hemispherical cover 11 is attached to the end plate 3b so as to cover the tip of the hose 6 and the forked branch of the wire 8.

Next, a method for painting the inner surface of a conduit using the inner surface coating device 2 composed of the sliding plug 1, the hose 6, and the wire 8 as described above will be described.

Reference numeral 12 denotes a conduit with open ends, which is made by welding the ends of a plurality of steel pipes 13 having tar-epoxy coatings 13a on their inner circumferential surfaces, and has a bent portion 12a that bends appropriately in the vertical and horizontal directions. The tar epoxy coating 15 disappears on the inner circumferential surface near the welded portion 14 due to the heat during welding, and the base 13a of the steel pipe 13 is exposed.

Further, a collar portion 12b is provided at the left end opening of the conduit 12.
are connected in series, and the entire conduit 12 is disposed within a groove 17 dug in the ground 16.

Reference numeral 18 denotes a guide tube, which is formed by connecting a curved tube 20 curved at right angles to the lower end of a straight tube 19 that is vertical. It is connected to the section 12b.

An enlarged diameter section 19a is formed at the upper end opening of the straight pipe 19, and a flange section 19b is connected to the opening edge, and a pressure gauge 21 is attached to one of the outer peripheral surfaces of the enlarged diameter section 19a. , and a connecting pipe 22 passing through the other outer peripheral surface is attached. This communication pipe 22 is connected to an air compressor 24 via an air hose 23.

As shown by the imaginary line in FIG. 1, the sliding plug body 1 is
After inserting the guide tube 18 downward from the enlarged diameter part 19a, the opening of the enlarged diameter part 19a is hermetically closed with a closure plate 25 from which the hose 6 and the wire 8 can be freely fed out. Install the tube 26.

Next, when the air compressor 24 is activated and air pressure is applied to the enlarged diameter portion 19a through the air hose 23, the sliding stopper 1 descends downward while sliding within the guide tube 18, and the bent tube 20 Inside the conduit 12, the elastic body 4 is elastically deformed to pass through the bend.
Go inside.

Simultaneously with the movement of the sliding plug 1, the hose 6 and wire 8 are pulled into the conduit 12, so the winch 9 is rewound as appropriate to let out the hose 6.

When the sliding plug 1 reaches the location within the conduit 12, that is, the place where the painting starts, the drive of the air compressor 24 is stopped, the sliding plug 1 is stopped, and a shutoff valve communicating with the inside of the enlarged diameter portion 19a is activated. Open (not shown) and
The inside of the guide tube 18 is communicated with the outside air.

Next, paint container 2 was transported for paint machine 7.
7 is filled with a paint 28 made of tar epoxy mixed with an appropriate viscosity, and connected with a hose 29.
When the sprayer 7 is connected and the sprayer 7 is driven, the paint 28 is injected into the conduit 12 from the nozzle head 5a of the sliding plug 1 through the hose 6.

The wire 8 is wound around the drum 10 by the winch 9, and the paint 28 is sprayed while simultaneously drawing out the hose 6 from the guide tube 18.

By drawing the sliding stopper 1 towards the guide tube 18 at the required speed, a tar epoxy coating 30 having a desired thickness, for example 0.5 mm, is formed in the conduit 12. It is being formed. The film thickness can be adjusted by adjusting the spray amount and moving speed.

When the tip of the nozzle head 5a reaches the left end of the conduit 12, that is, when the painting end position is reached, the spraying of the paint 28 is stopped, the closing plate 25 is removed from the guide tube 18, and the sliding stopper 1 is taken out.

After that, when the joint between the guide tube 18 and the conduit 12 is removed, the quick-drying paint 28 dries rapidly.
The coating film 30 is fixed.

After the painting work is completed, as shown in FIG. 3, the inner circumferential surface of the conduit 12 is covered with a coating film 30 having a uniform thickness over the coating 15, and the inner circumferential surface of the conduit 12 is covered with a coating film 30 having a uniform thickness. A portion of the substrate 13a is similarly coated with tar epoxy.

(Modification) In the above example, the painting work on the inner surface of the conduit was explained with the conduit installed in a trench under the ground. Instead of the guide tube 18 described above, a horizontal guide tube may be used or the moving nozzle 1 may be inserted directly into the conduit.

Alternatively, by measuring the amount of winding of the cable, a certain area corresponding to the welded part 14 of the conduit 12, for example, only the exposed part of the substrate 13a, may be painted intermittently.

(Effects of the Invention) According to the method for painting the inner surface of a conduit according to the present invention, the inner surface of the conduit can be coated mechanically and efficiently without manual intervention.

Furthermore, since the sliding plug cleans the inside of the pipe on its outward journey and paints it on its return journey, it has the advantage that cleaning inside the pipe after welding can be completed in one step. Another advantage is that even if the coating on the conduit is damaged, the damaged area can be repaired because it is painted on the return journey.

In particular, as a method for repainting the inner coating of steel pipes used for waterworks after welding, the method has the advantage of being simple and quick, and of reducing work costs.

Furthermore, the apparatus for coating the inner surface of a conduit according to the present invention has the advantage that it is possible to mechanically coat the inner surface of a small diameter conduit, which has heretofore been considered impossible.

In particular, if a flexible elastic body is fitted to the outer peripheral surface of the sliding stopper, even if the conduit is a conduit system having complicated bends, the inner surface can be coated. As a result, the inner surfaces of small-diameter pipes, which have been neglected until now, can be painted, making it possible to achieve great results in preventing harmful effects such as red water in water supplies.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conduit for explaining an embodiment of the conduit inner surface coating apparatus and the method for coating the inner surface of the conduit according to the present invention, and FIG. 2 is an enlarged view of the sliding stopper shown in FIG. 1. The vertical cross-sectional view, Figure 3, is the - of Figure 1.
FIG. 4, which is a vertical cross-sectional view of the conduit along the line, is a partially cutaway side view for explaining a conventional welded portion between steel pipes. 1...Sliding plug body, 2...Inner surface coating device, 3...
Main body, 3a, 3b... end plate, 5... nozzle pipe,
5a... Nozzle head, 6... Hose, 7... Painter, 8... Wire (cable), 9... Winch,
12... Conduit, 13... Steel pipe, 14... Welded part,
15... Coating, 17... Groove, 18... Guide tube, 2
1... Pressure gauge, 22... Communication pipe, 23... Air hose, 24... Air compressor, 25... Closure plate, 2
6...Guide tube, 27...Paint container, 29...Hose.

Claims (1)

[Scope of Claims] 1. A sliding stopper with a nozzle head protruding from the front end surface of a cylindrical main body and a towing cable and a paint pressure hose connected to the rear end surface is installed in a conduit in an almost airtight state. At the same time, air pressure is applied to the rear end side of the sliding plug to move it to the coating start position in the conduit, and then the traction cable is inserted from the entrance side of the conduit. A method for painting the inner surface of a conduit, which comprises spraying paint from the nozzle head to form a coating film on the inner circumferential surface of the conduit while retracting the sliding plug by pulling the plug. 2. A sliding stopper with a traction cable attached to the rear and a nozzle head on the front is moved forward in the conduit by air pressure, then retreated by winding up the cable, and at the same time the paint is applied. This is an internal coating device used in a coating method that sprays from a nozzle head to coat the inner surface of a conduit, and has a nozzle head in the center of the front end of a cylindrical main body, and the outer circumferential surface is almost airtight with the inner circumferential surface of the conduit. a sliding stopper fitted with an elastic body capable of slidingly contacting the sliding stopper; a traction cable having a distal end connected to the rear end surface of the sliding stopper and a proximal end wound around a winding device; What is claimed is: 1. An inner surface coating device for a conduit, comprising a hose for pumping paint, the distal end of which is connected to the nozzle head, and the proximal end of which is connected to a coating machine. 3. The inner surface coating device for a conduit according to claim 2, wherein the elastic body is made of a cellular polyurethane foam.