JPH0681385B2 - Construction method for small-diameter pipelines in the main pipeline - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a small-diameter conduit in a main conduit.

Conventional technology and its problems Communication cables and electric power cables are often inserted into underground pipelines, especially in urban areas. There is usually an empty space in the existing buried pipeline used for inserting this kind of cable, and this empty space is used for inserting communication cables and other various cables due to the increasing demand due to the sophistication and diversification of communication technology. There is a tendency. However, since this type of conduit has a single passage inside, the existing old cable may be damaged when a new cable is inserted, and various cables of different uses and types may be inserted into a single passage. Then, the insertion state becomes cluttered, it becomes difficult to distinguish the cables, and it is impossible to replace the cables, which is inconvenient for wiring work and other maintenance.

Such a problem can be solved by forming a small-diameter pipe line in an existing buried pipe line so that a cable can be inserted into each small-diameter pipe line. However, if such a small-diameter pipe is formed by adding pipe members of a fixed size as in the case of forming a normal pipe, it requires a large amount of manpower and time to add the pipe, which increases the construction cost. This is practically impossible due to the construction cost limitation.

The present invention has been made for the purpose of eliminating such conventional problems.

Means for Solving the Problems The present invention uses a roll of a hard plastic sheet having a width corresponding to the circumferential length of a small-diameter conduit as a material for forming a small-diameter conduit, and the sheet is heated and softened. While pulling out from the roll toward the main pipe inlet, insert into the main pipe while forming the circular pipe from the sheet and cooling and solidifying the circular pipe forming part in the process of reaching the main pipe inlet. The present invention relates to a method for forming a small-diameter pipeline inside a main pipeline, which is characterized in that

Effect According to the method of the present invention, the hard plastic sheet is pulled out from the roll under the heat-softened state while forming the circular pipe portion during the course of reaching the inlet of the main pipe line, and cooling and solidifying the inside of the main pipe line. Since it will be inserted in parallel and linearly to
Even if a small-diameter pipe with an ultra-long span of 200 to 400 m is to be formed, it can be constructed without the troublesome work of adding pipes.

Examples The following will explain one embodiment of the method of the present invention with reference to the accompanying drawings.

1 to 2 schematically show the whole one implementation situation of the method of the present invention.

The main pipeline (3) between the vertical shafts (1) and (2) (eg manholes) is laid in a substantially straight line like an ordinary power tube, and has a length of, for example, about 200 to 400 m, and the inside thereof. A cable (4) is inserted through the.

The hard plastic sheet (6) used to form the small diameter conduit (5) (see FIG. 6) in the main conduit (3) has a width corresponding to the circumferential length of the small diameter conduit (5) and a main conduit. It has a length approximately equivalent to the total length of (3), and rolls (6
It will be delivered in the form of a).

The sheet (6) is thermoplastic and is softened by heating, and under this heat-softened state, the sheet (6) is wound into a roll (6a) and unwound from the roll (6a).

The sheet (6) is formed from a thermoplastic resin having a relatively low softening point (for example, 60 to 100 ° C.), such as polyvinyl chloride, polyethylene, or polypropylene, in order to heat and soften the sheet by applying a heating fluid such as steam. To be done.

FIG. 3 shows an example of manufacturing the roll (6a) of the sheet (6), in which a pipe (6 ') having the same diameter as the small diameter conduit (5) extruded from the extruder (7) is placed in a cooling tank ( After passing through 8), the cutter (10) and the vertical rolls (1) following it are reheated by steam in the heating chamber (9) to soften them.
It is obtained by incising in cooperation with the horizontal roll (1) and the horizontal roll (12) and rolling it into a roll while unfolding. The sheet (6) thus obtained tends to return to the original tubular shape in the heat-softened state, so that the tubular shape can be easily formed from the sheet (6).

Rigid plastic sheet (6) as shown in FIG.
The roll (6a) is rotatably received on a pedestal (13) installed in the vicinity of the vertical shaft (1), and is stored in the heat insulating casing (14) in this state.

Inside the vertical shaft (1), split horizontal insulation duct (15)
However, the main axis (3) is installed in front of the entrance of the main path (3) so that the central axes are substantially common, and the cable (4) extends horizontally through the inside. The rear portion of the horizontal duct (15) is inclined obliquely upward, and the rear inclined portion (15a) is connected to the outlet duct (14a) of the heat insulating casing (14) via the heat insulating inclined duct (16). There is.

The horizontal duct (15) has an outlet pipe (15b) protruding forward at the front end, the outlet pipe (15b) faces the inlet of the main pipe (3), and the inside of the cable (4) is Penetrates. The outlet pipe (15b) has an inner diameter corresponding to the outer diameter of the small diameter conduit (5) and is made of a metal having good thermal conductivity. A cooling fluid supply device (17) is installed above the outlet pipe (15b).

In the horizontal duct (15), between the lower guide roll (18b) and the inlet of the outlet tube (15b), the sheet (6) is changed from a flat shape to an arc shape and finally to a shape close to a substantially circular tube shape. A deformation processing member (19) for deforming is installed. The deformation processing member (19) has a downward gutter shape, and the inlet side has a shallow arc shape, and this arc shape gradually becomes deeper toward the outlet side, and finally becomes a substantially circular pipe. Based on the shape, it is connected to the inlet side of the outlet pipe (15b). The sheet (6) is made to have a circular tubular shape through a flat shape, an arc shape, and finally while slidingly moving in the member (19),
A cable (4) penetrates the inside. The deformation processing state of the sheet (6) is schematically shown in FIG. 4 in the order of points A, B and C (see FIG. 1). The inside of the horizontal duct (15) is closed in front of the lower guide roll (18b) by a rubber film (25) for preventing thermal fluid outflow, and the rubber film (25) has a cut through which the sheet (6) can pass. (25a) is formed.

At the start of construction, the sheet (6) is preliminarily operated, passes through the upper and lower guide rolls (18a) (18b), and the deformation processing member (19) in order, and then the cable (from the outlet pipe (15b) to the circular pipe ( 4) is pulled out in such a manner as to contain it, and is connected to the tow rope (22) at the tip of the circular tubular portion (6b) via the connecting hardware (21). The tow rope (22) is preliminarily passed through the main pipeline (3), and its base end side is wound up on a winch (23) installed on the other vertical shaft (2) side as shown in FIG. . The connecting hardware (21) has a split ring shape, and the cable (4) penetrates through the ring as shown in FIG.

When a heat fluid such as steam is supplied to fill the heat insulating casing (14) and the ducts (16) and (15) connected to the heat insulating casing (14) through the conduit (20) in the state shown in FIGS. ) Is softened by heating with steam, and is ready to be pulled out from the roll (6a). Under this heat-softened state, the winch (2
3) is operated and the seat (6) is pulled through the tow rope (22).
When the sheet (6) is pulled out from the roll (6a), the sheet (6) passes between the upper and lower guide rolls (18a) and (18b) in a flat shape and also passes through the deformation processing member (19) to move to the fourth position.
As shown in the figure, while being deformed from a circular arc shape to a circular tube, it finally becomes a circular tube and reaches the outlet pipe (15b).
During the passage in 5b), it is cooled and solidified by the cooling fluid supplied from the supply device (17), and is inserted into the main conduit (3) in the state of a rigid circular tube. By continuing to pull the seat (6) with such a rope (22), a small diameter conduit (5) is formed over the entire length of the main conduit (3) as shown in FIG. You can In this embodiment, the connecting fitting (21) moves on the cable (4), and the cable (4) is inserted into the small-diameter conduit (5) as it moves, so that the cable is inserted into the main conduit (3). The small-diameter conduit (5) can be formed while the (4) is still inserted, and the cable (4) can be inserted into the conduit (5) at the same time. The deformation processing of the sheet (6) into a tubular shape may be performed while the deformation processing member (19) is used as a heater and the sheet (6) is heated by the portion (19).

Effect The method of the present invention is a method of continuously forming a small-diameter conduit in the main conduit using a roll of a hard plastic sheet, so such a small-diameter conduit is, for example, an ultra long span of 200 to 400 m. Can be carried out as one construction manager, and the construction cost can be reduced to a practicable level. Further, since the method is such that the circular pipe portion is formed from the sheet and is inserted into the main pipe line, even if an old cable is inserted into the main pipe line, it can be carried out with the cable inserted.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a vertical shaft portion on one side showing an embodiment of the present invention, FIG. 2 is a schematic explanatory view of the vertical shaft portion on the other side, and FIG. 3 is a schematic explanatory view showing an example of manufacturing a roll of a hard plastic sheet. 4 and 5 are explanatory views showing the processing state of the processing member step by step, FIG. 5 is an enlarged vertical sectional view of the connecting metal object, and FIG. 6 is a schematic explanatory view showing the formation state of the small diameter pipe. In the figure, (1) and (2) are vertical shafts, (3) is the main pipeline,
(4) is a cable, (6) is a seat, (13) is a stand,
(14) is a heat insulation casing, (15) is a horizontal duct, (16)
Is an inclined duct, (17) is a supply device, (18a) and (18b) are guide rolls, (19) is a deformation processing member, (20) is a support tool, (21) is a connecting hardware, and (22) is a tow rope. Is.

Claims (1)

[Claims] 1. A roll of a hard plastic sheet having a width corresponding to the circumferential length of a small diameter conduit is used as a material for forming a small diameter conduit, and the sheet is directed toward the main conduit inlet from the roll under a heat-softened state. It is characterized in that it is inserted into the main pipe while forming a circular pipe from the sheet and cooling and solidifying the circular pipe forming part in the course of reaching the main pipe inlet while pulling out. A small diameter pipeline forming method inside the main pipeline.