Method for manufacturing pipe-lining material

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing a pipe-lining material for lining a deteriorated existing pipe.

2. Description of the Related Art

Pipe channel lining methods are used for repairing an existing pipe without unearthing the existing pipe in the case that the underground existing pipe such as a clean water pipe, sewage pipe, or the like has deteriorated. With this method, the pipe-lining material composed of a tubular resin absorbent material in which a thermosetting resin has been impregnated is inserted into an existing pipe by eversion or drawing, and is expanded by air pressure or the like and held in a state that the pipe-lining material is pressed against the internal peripheral surface of the existing pipe. In this state, the pipe-lining material is heated, and the thermosetting resin impregnated in the tubular resin absorbent material is cured to line the existing pipe (e.g., Japanese Laid-open Patent Application Nos. 2006-130899 and 2007-125703 and the like).

The resin absorbent material of the pipe-lining material is composed of a soft felt or the like, and a soft tube composed of a highly airtight plastic film is heat-fused to the external peripheral surface of the resin absorbent material (the internal peripheral surface when the pipe-lining material is everted) to form a coating layer. The tube protects the curable resin impregnated in the tubular resin absorbent material and prevents the curable resin from being in contact with the exterior. In the case that the pipe-lining material is everted and inserted into a pipeline, the heat-fused tube becomes the internal peripheral surface, thereby preventing the resin impregnated in the tubular resin absorbent material from being in direct contact with compressed air when the pipe-lining material is expanded using the compressed air in the subsequent lining process, or preventing the resin from being in direct contact with heat medium in the case that the resin is heated by the heat medium, such as steam, hot water, or the like.

In the case that the tube is heat-fused to the external peripheral surface of the resin absorbent material of the pipe-lining material, the tubular resin absorbent material is conventionally expanded inside the tube to be in close contact with the internal peripheral surface thereof. The tube is then conveyed into a columnar furnace provided with a heater that extends in the axial direction. The tube and the tubular resin absorbent material conveyed into the furnace are moved through the furnace toward the exit thereof, and heated from the exterior during movement, thereby the tube is heat-fused to the tubular resin absorbent material.

With such a method, a mechanism is required for moving the tube and the tubular resin absorbent material through the furnace, and the tube and the tubular resin absorbent material must be moved while the center axis of the furnace is aligned with the center axis of the tubular resin absorbent material and the tube that are both expanded in a columnar shape. Without such movement, the distance from the heater to the tube and the tubular resin absorbent material differs in the upper part and the lower part of the furnace, so that non-uniformities are generated in heating and thereby the tube cannot be uniformly heat-fused to the tubular resin absorbent material. When heat-fusion is insufficient, there is a problem that the resin impregnated in the tubular resin absorbent material is not adequately cured and thereby reliable lining becomes unavailable.

On the other hand, the entire heater extending over the entire length of the furnace must be energized when the distal end of the tube and the tubular resin absorbent material are conveyed into the furnace. In addition, electricity must be continuously fed to the heater until the rear end thereof pass out of the exit of the furnace. These cause another problem that wasteful heating and power consumption is inevitable.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method for manufacturing a pipe-lining material in which a tube is uniformly and efficiently heat-fused to the tubular resin absorbent material, and a high-quality pipe-lining material can be manufactured using a simple method.

According to the present invention, a method is proposed for manufacturing a pipe-lining material comprising a tubular resin absorbent material covered with a tube comprised of an airtight plastic film, wherein the tube is heat-fused to an external peripheral surface of the tubular resin absorbent material. The method comprises inserting the tubular resin absorbent material into the tube, and expanding the tubular resin absorbent material and the tube in a columnar shape so as to bring the tubular resin absorbent material into close contact with the internal peripheral surface of the tube; winding a heater in close contact with the external peripheral surface of the tube thus expanded; and heating the tube and the tubular resin absorbent material by energizing the heater to heat-fuse the tube to the external peripheral surface of the tubular resin absorbent material.

In the present invention, the heater is wound in close contact with the external peripheral surface of the tube that coves the tubular resin absorbent material. The tube and the tubular resin absorbent material are then heated by energizing the heater, so that the tube is heat-fused to the tubular resin absorbent material. Therefore, a mechanism for moving the tube and the tubular resin absorbent material is not required, and the tube can be uniformly heat-fused to the tubular resin absorbent material without generating heating non-uniformities, thereby manufacturing a high-quality pipe-lining material in a simple manner.

In the present invention, the tube and the tubular resin absorbent material can be heated without waste, and the tube can be efficiently heat-fused to the tubular resin absorbent material using a small amount of power because the heater is wound in close contact with the external peripheral surface of the tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the pipe-lining material when the tubular resin absorbent material has been inserted into a tube and expanded;

FIG. 2A is a perspective view showing the tubular resin absorbent material and the tube around which a heater has been wound, and FIG. 2B is a perspective view showing the tubular resin absorbent material and the tube around which a plurality of heaters has been wound; and

FIG. 3 is an illustrative view showing the connections of the heating wires of the heater.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, referring to the drawings, description is made about embodiments of the present invention. The description is herein made as regards a method for manufacturing a pipe-lining material used to line a sewage pipe as an existing pipe. However, the present invention is not limited to this case, but can be applied to other cases in which the method for manufacturing a pipe-lining material is used to line a clean water pipe, an agricultural water pipe, or the like.

FIG. 1 shows a process for manufacturing a pipe-lining material used to repair or rehabilitate an existing pipe. A pipe-lining material 1 comprises a soft tubular resin absorbent material 10 whose external peripheral surface 10a is covered with a soft tube 11 composed of polyethylene, polypropylene, nylon, vinyl chloride, or another highly airtight plastic film.

The tubular resin absorbent material 10 is composed of a matte, a woven, or a nonwoven using polyamide, polyester, polypropylene, or another plastic fiber; a matte or a woven using glass fiber; or a matte, a woven, or a nonwoven that combines the use of the above-noted plastic fiber and fiber glass. The tubular resin absorbent material 10 is impregnated with unsaturated polyester resin, vinyl ester resin, epoxy resin, or another uncured liquid thermosetting resin.

In order to manufacture such a pipe-lining material, the tubular resin absorbent material 10 is inserted into the tube 11, and a tubular inner liner 12 that is closed at one end (the right side in FIG. 1) is inserted into the tubular resin absorbent material 10 so that the tubular resin absorbent material 10 can be held between the tube 11 and the inner liner 12.

A hole is opened in the tubular resin absorbent material 10 and the tube 11, and a vacuum hose 13 is attached to the hole to suck the tubular resin absorbent material 10 by vacuum. Compressed air is fed from the open end (left side of FIG. 1) of the inner liner 12. This causes the tube 11, the tubular resin absorbent material 10 and the inner liner 12, which are initially in a flat shape, to be all expanded in a columnar shape, as shown in FIG. 1. The tubular resin absorbent material 10 is brought into close contact with the internal peripheral surface of the tube 11. The inside diameter of the tube 11 substantially coincides with the outside diameter of the tubular resin absorbent material 10 when both are expanded in a columnar shape, and the inside diameter of the tubular resin absorbent material 10 substantially coincides with the outside diameter of the inner liner 12 when both are expanded in a columnar shape.

In FIG. 1, the vacuum hose 13 is provided in only a single location, but the vacuum hose is ordinarily attached in a plurality of locations in accordance with the length of the pipe-lining material in order to efficiently carry out the vacuum suction of the tubular resin absorbent material.

As shown in FIG. 2A, the tube 11, the tubular resin absorbent material 10 and the inner liner 12 are kept in an expanded state, and a heater 20 is wound in close contact with the external peripheral surface of the tube 11 that covers the tubular resin absorbent material 10.

The heater 20 is such a heater in which Nichrome wires or other heating wires 20b are arranged in a periodic serpentine fashion at an equal pitch p (e.g., 7.5 mm) inside a rectangular or square insulating cloth (shown as an imaginary line in the drawing) that has one side Y and another side Y′, as shown in FIG. 3. Y′ is substantially equal to or greater than the outer circumference of the tube 11, and has a length in which the both ends of the heater 20 are partially overlapping with each other (FIG. 2A) when the heater 20 is wound in close contact with the tube 11.

A heating wire 20b is turned back when the heating wire 20b has extended up to a predetermined distance in the Y′ direction, and is then turned back again when the heating wire 20b has extended up to the same distance in the opposite direction thereof, as shown in FIG. 3. This turning back is repeated so that the heating wire extends in a periodic serpentine fashion in the lengthwise direction of the pipe-lining material at a pitch p. The heating wire 20b is connected to a plug 20c at one end, and the heating wire 20b can be energized and heat can be generated in the heating wire 20b by plugging the plug 20c into a power source outlet 20d of the main line 21. The quantity of heat generated by the heating wire is uniform over the entire heater 20 because the heating wire 20b is uniformly distributed over substantially the entire heater.

When the pipe-lining material 1 has considerable length, a plurality of heaters 20 is disposed adjacent to each other and wound in close contact with the external peripheral surface of the tube 11, as shown in FIG. 2B. In this case, the smallest integer Z that satisfies the expression Y*Z>X (where * is the reference symbol for multiplication) is calculated for the case in which X is greater than Y, wherein X is the length of the pipe-lining material in the axial direction (the length of the tube 11), and Y is the length over which one side of the heater 20 extends in the length direction of the pipe-lining material. The calculated number Z of heaters 20 is arranged adjacent to each other and wound in close contact with the external peripheral surface of the tube 11. The Z number of heaters 20 is connected in parallel by plugging the plug 20c of each heater 20 into the power source outlet 20d.

In FIGS. 2A and 2B, the first heater 20 (left end in the drawing) is wound slightly to the right from the distal end of the tube 11 in order to facilitate an understanding of the present invention. However, in actual practice, the left end of the heater 20 and the distal end of the tube 11 are disposed in substantially matching positions.

In the case of the pipe-lining material 1 shown in FIG. 2, the length X in the pipe lengthwise direction is greater than the Y value of one side of the heater 20. Therefore, Z number of heaters 20 is prepared using the formula described above, and the plugs 20c are plugged into the outlets 20d to connect the Z number of heaters 20 in parallel. In the example of FIG. 2B, three heaters 20 are wound around the tube 11 and connected in parallel. However, the plugs of the heaters and the outlets are omitted in the drawing in order to avoid complexity.

A predetermined number Z of heaters 20 is wound around the tube 11, and the plugs 20c are plugged into the power source outlets 20d to energize the heaters 20, respectively. The tube 11 and the tubular resin absorbent material 10 are uniformly heated, and the tube 11 is heat-fused to the tubular resin absorbent material 10, thereby forming a coating layer thereon.

Thus, the tubular resin absorbent material and the tube covering the tubular resin absorbent material can be entirely heated using a predetermined number of connected heaters even when the tubular resin absorbent material of the pipe-lining material is long. Therefore, heating can be uniformly and efficiently carried out, and the tube can be heat-fused to the tubular resin absorbent material with high quality.

The portions in which the heaters 20 are adjacent to each other are less likely to be uniformly heated. Therefore, a thin metal sheet 30 (e.g., aluminum foil) having good thermal conductivity is wound around the tube 11 as shown by the imaginary line in FIG. 2B. The heaters 20, 20 are then placed adjacent to each other and wound on the metal sheet, thereby rendering the quantity of heat to be uniform. The sheet 30 is shown in only one location in FIG. 2B, but the sheet is also wound around other adjacent heaters.

Thus, when the tube 11 has been heat-fused to the external peripheral surface of the tubular resin absorbent material 10, vacuum suction via the vacuum hose 13 is stopped, and the supply of compressed air to the inner liner 12 is discontinued. This allows the tube 11, the tubular resin absorbent material 10 and the inner liner 12 to contract. The inner liner 12 is then pulled out from the tube 11 and the tubular resin absorbent material 10.

A resin that cures by heating or by radiation of light, or a curable resin that cures at a normal temperature is impregnated in the tubular resin absorbent material 10 using a known method (described, e.g., in Japanese Laid-open Patent Application No. 2001-108555). In other words, the curable resin is injected into the tubular resin absorbent material 10, and the tubular resin absorbent material 10 is then subjected to vacuum suction to produce negative pressure therein in order to impregnate the curable resin in the tubular resin absorbent material 10. Accordingly, it is possible to manufacture a pipe-lining material in which a tube composed of an airtight plastic film is heat-fused to the external peripheral surface of the tubular resin absorbent material and a curable resin is impregnated therein.

The pipe-lining material thus manufactured is inserted by eversion or by drawing into an existing pipe so that the tube becomes the internal peripheral surface. The pipe-lining material is then expanded by air pressure or the like so as to be pressed against the internal peripheral surface of the existing pipe. In this state, the pipe-lining material is heated or irradiated with light in order to cure the curable resin impregnated in the tubular resin absorbent material and line the existing pipe.