JPH03218211A - Laying method for cable in duct line - Google Patents

Abstract

PURPOSE:To reduce friction resistance by simultaneously drawing a cable and a subduct into a duct line thereafter drawing an extension cable into the subduct. CONSTITUTION:A cable 1 and a subduct 4 are simultaneously drawn into a duct line 2 and laid by pulling a lead wire 6 in an opposite side end of the duct line 2 by a winch or the like. Here the cable 1 and the subduct 4 can be avoided from being entangled each other by twisting because twists of the lead wire 6, cable 1 and the subduct 4 are eliminated respectively by a lead wire twist back metal fixture 8, cable twist back metal fixture 10 and a subduct twist back metal fixture 12. In this way, draw-in laying can be performed without giving damage to the subduct 4 by remarkably reducing friction force of acting on the subduct 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for laying a cable in a conduit.

[Conventional technology] Conventionally, as shown in Figure 3, cables such as power cables 1
When installing an additional cable 3 such as a metal cable or an optical fiber cable in a conduit 2 that has already been installed, a rod for wiring is passed through it from one end of the conduit 2, and the When the tip of the wire rod comes out to the other end of the conduit 2, connect the tip of the extension cable 3 to the tip of the wire rod, and connect the proximal end of the wire rod to the other end of the conduit 2. The extension cable 3 was drawn into the conduit 2 by taking it off at one end of the conduit 2.

[Problems to be Solved by the Invention] However, in this cable extension method, the extension cable 3 is drawn through the gap between the inner wall of the conduit 2 and the cable 1. There is a problem in that the cable 1 receives large frictional resistance from both the inner wall of the channel 2 and the cable 1, which increases the tensile force of the extension cable and damages the extension cable 3.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for laying an extension cable in a conduit while suppressing frictional resistance.

[Means for Solving the Problems] To explain the means of the present invention for achieving the above object, the method of laying a cable in a conduit according to the present invention includes simultaneously drawing a cable and a subduct into a conduit, After that, an additional cable is drawn into the subduct.

[Operation] When the cable and subduct are drawn into the conduit at the same time and laid in this way, the frictional force acting on the subduct is significantly reduced compared to when the subduct is drawn in and laid separately later, which prevents damage to the subduct. It is possible to carry out recessed installation without having to provide any cables. When an extension cable is later drawn into and laid in such a subduct, the extension cable can be drawn and laid with lower frictional force than in the case where there is no subduct.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 and 2.

In this embodiment, when a cable 1 such as a power cable is drawn into the conduit 2, a subduct 4 made of a corrugated flexible pipe is drawn in and laid at the same time.

As the drawing means, a pooling device 5 as shown in the figure is used. The pooling device 5 has a lead wire 6
A lead wire twisting fitting 8 is connected to the end of the cable through a shackle 7, and a cable twisting fitting 10 is connected to the lead wire twisting fitting 8 via a shackle 9. A subduct twisting fitting 12 is connected to the fitting 8 via a wire 11, and the cable twisting fitting 10 and the subduct twisting fitting 12 are arranged such that the subduct twisting fitting 12 is located at the rear. The structure is such that the positions are shifted in the longitudinal direction.

The cable twisting fitting 10 of the pooling device 5 includes:
A cable 1, such as a power cable, is connected via a shackle 13 and a pulling eye 14. Further, the subduct 4, such as a corrugated flexible tube made of plastic or aluminum, is connected to the subduct twisting fitting 12 of the pooling device 5 via a pulling eye 15.

The lead wire 6 is passed through, for example, a wire passing rod from the opposite end of the conduit 2, and when the tip of the wire passing rod protrudes to the illustrated end of the conduit 2, Connect the tip of the lead wire 6 to the tip of the wire rod, and insert the lead wire 6 into the conduit 2 by pulling the base end of the wire rod from the opposite end of the conduit 2. This is done by pulling in.

In this state, the cable 1 and the subduct 4 are bowed and laid in the conduit 2 at the same time by pulling off the lead wire 6 at the opposite end of the conduit 2 using a winch or the like. At this time, the twisting of the lead wire 6 is eliminated by the lead wire twisting fitting 8, the twisting of the cable 1 is eliminated by the cable twisting fitting 10, and the twisting of the subduct is eliminated by the subduct twisting fitting 12, so that the cable 1 and It is possible to avoid entanglement between the subduct 4 and the subduct 4 due to twisting.

Moreover, especially when the subduct 4 is an FRP pipe or a corrugated plastic pipe, the subduct 4 is light and elastic, so that it can avoid being wound around the cable 1 by being blown away.

When the subducts 4 are laid simultaneously in this way, the frictional force acting on the subducts 4 is significantly reduced compared to when the subducts 4 are laid separately and later, and the cable can be laid without damaging the subducts 4. I can do it. In addition, in the case of subduct 4 made of FRP pipe or corrugated plastic pipe, cable 1
Since the extension cable 3 can be laid without being wrapped around the subduct 4, it becomes substantially straight, which has the advantage of not increasing frictional resistance when the extension cable 3 is later drawn into the subduct 4 and laid.

Note that the extension cable 3 should be laid in the subduct 4 after the cable 1 and the subduct 4 are drawn in at the same time.
This may be done immediately, or may be done after a period of time, such as when there is a demand for it.

Furthermore, it goes without saying that the extension cable 3 is not limited to a metal cable or an optical fiber cable, but may also be a power cable or the like.

Furthermore, the number of subducts 4 is not limited to just one, but a plurality of subducts 4 can be laid simultaneously together with the cable 1.

[Effects of the Invention] As explained above, the method of laying a cable in a conduit according to the present invention involves pulling and laying the cable and subduct into the conduit at the same time, compared to the case where the subduct is pulled in and laid separately later. , the frictional force acting on the subduct is significantly reduced, and it is possible to carry out lead-in installation without damaging the subduct. Since the extension cable is drawn in and installed later into such a subduct, the extension cable can be drawn in and installed with lower frictional force than in the case where there is no subduct.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of the implementation state of the installation method according to the present invention, FIG. 2 is a cross-sectional view showing an example of the internal structure of the pipeline installed by the method of the invention, and FIG. FIG. 3 is a cross-sectional view showing an example of a structure inside a pipe. DESCRIPTION OF SYMBOLS 1... Cable, 2... Conduit, 3... Extension cable, 4... Subduct, 5... Pooling device, 6
... Lead wire, 8... Twisting fitting for lead wire, 10... Twisting fitting for cable, 11...
Wire 12...Twisting fitting for subduct. 7

Claims (1)

[Claims] 1. A method for laying a cable in a conduit, the method comprising drawing a cable and a subduct into the conduit at the same time, and then drawing an additional cable into the subduct.