JPH03215112A - Protection of existing cable in conduit - Google Patents

Abstract

PURPOSE:To protect the outer periphery of an existing cable in a conduit by employing a protective pipe of the structure in which one crack is formed longitudinally at one position in a circumferential direction. CONSTITUTION:A cable protective pipe 7 of a crack opening cable guide jig is engaged with the cable 1 of a conduit 2 in a state that a detachable spacer 10 is removed, and the spacer 10 is then mounted at a crack opening frame 6 with a nut. A crack opening frame 6 of a crack opening cable guide jig 5 is press-fitted in the crack 4A of a protective pipe 4 from the closed end side to open the crack 4A. When the pipe 4 is pressed into the conduit 2 in this state, the crack 4A of the pipe 4 is sequentially opened by the frame 6, and the pipe 4 covers the cable 1 while protecting it with the pipe 7 at the position of the jig 5.

Description

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

[Prior Art] Conventionally, as shown in FIG. 5, when an extension cable 3 is installed in a conduit 2 in which an existing cable 1 such as a metal communication cable or an optical fiber cable exists, the extension cable 3 is simply installed. Expansion work was carried out by pulling cable 3 with a pulling wire.

[Problems to be Solved by the Invention] However, such an extension method has a problem in that the existing cable 1 is rubbed or pulled by the extension cable 3, causing damage to the existing cable 1. Further, in the case of a large diameter and heavy extension cable 3, there is a problem in that the extension cable 3 rides on the existing cable 1 and the existing cable 1 is easily damaged.

An object of the present invention is to provide a method for protecting existing cables in a conduit, which can protect existing cables when adding cables.

[Means for Solving the Problems] To explain the means of the present invention for achieving the above object, the present invention provides a method for protecting existing cables installed in a conduit for protecting existing cables installed in a conduit. In the method, a protective tube having a single longitudinal crack provided at one location in the circumferential direction is successively opened from one end and placed over the existing cable, and the portion of the protective tube covered over the existing cable is sequentially opened. It is characterized in that it is supplied into the pipeline and the outer periphery of the existing cable is protected by the protection tube.

[Function] With the above arrangement, the protection tube can be supplied from one end of the conduit to protect the outer periphery of the existing cable with the protection tube. Therefore, the existing cable can be protected by the protection tube when the extension cable is drawn in.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 to 4.

In this embodiment, as shown in FIGS. 2(A) and 2(B), a flexible protective tube 4 made of a corrugated plastic tube is provided with a single vertical crack 4A at one location in the circumferential direction. use

Further, in order to open the crack 4A of the protective tube 4 and cover the existing cable 1 with the protective tube 4, a crack opening/cable guide jig 5 as shown in FIG. 3 is used. The jig 5 has V
It has a character-shaped crack opening frame 6, and the opening end of the V-shaped crack opening frame 6 has a structure having an opening width for opening the crack 4A of the protection tube 4 beyond the outer diameter of the existing cable 1. ing. A cable protection pipe 7 is installed diagonally on the open end side of the split open frame 6, and a fixed spacer 8 and a nut are installed on the open end side of the split open frame 6 to prevent the gap from narrowing due to external pressure. A detachable spacer 10 that can be attached and detached at 9 is provided.

Further, a retaining wire 11 is attached to a position near the closed end of the jig 5 to restrain the jig 5 from moving.

The cable protection pipe 7 has a structure with one or two cracks 7A in the longitudinal direction so that it can be fitted into the existing cable 1 from the middle.

As shown in FIG. 1, the method of protecting an existing cable in a conduit according to the present embodiment is to prevent cracks from opening in the existing cable 1 that protrudes from the conduit 2 at one end of the conduit 2. Fit the cable protection pipe 7 of the cable guide jig 5 with the removable spacer 10 removed, and then attach the removable spacer 10 to the cracked frame 6 with a nut 9.
The existing cable 1 is made to pass diagonally through the crack opening frame 6. Next, the crack opening frame 6 of the crack opening/cable guide jig 5 is compressed from the closed end side to the crack 4A of the protective tube 4 to open the crack 4A.

In this state, when the protective tube 4 is pushed into the conduit 2 with the crack opening/cable guide jig 5 held back by the retaining wire 11, the cracks 4A of the protective tube 4 are successively opened by the crack opening frame 6. At the same time, the protective tube 4 is sequentially placed over the existing cable 1 while being protected by the cable protection pipe 7 at the position of the crack opening/cable guide jig 5. By using the cable protection pipe 7 in this way, when the protection tube 4 is placed over the existing cable 1, it is possible to prevent the existing cable 1 from being damaged by the edge of the crack 4A of the protection tube 4. The opening of the crack 4A of the protection tube 4 is automatically closed due to elasticity after passing through the crack opening/cable guide jig 5. The part of the protective tube 4 that covers the existing cable 1 is
The protective tube 4 is moved along the existing cable 1 in the conduit 2 by the pressing force applied thereto, and the entire length of the existing cable 1 in the conduit 2 is protected by the protective tube 4 as shown in FIG. I can do it.

Therefore, in the state shown in FIG. 4, it is possible to prevent the existing cable 1 from being damaged when the extension cable 3 is drawn in.

Note that when the total length of the pipe line 2 is very long, it is not possible to feed the protective tube 4 into the pipe line 2 by simply pushing it, so as shown in FIG. It may be retracted, or a combination of pushing and retracting may be used.

Furthermore, although it is preferable that the protection tube 4 has a corrugated structure, it may also be a tube with a non-corrugated structure.

[Effects of the Invention] As explained above, in the present invention, a protection tube having a structure in which one vertical crack is provided at one location in the circumferential direction is used, and the cracks of the protection tube are sequentially opened from the end to remove the existing cable. Cover it with
Since the portion of the protective tube that covers the existing cable is sequentially supplied into the conduit, the outer periphery of the existing cable in the conduit can be protected by the protective tube. Therefore, when an extension cable is drawn into a conduit where an existing cable exists, the protection tube can protect the existing cable from being damaged when the extension cable is drawn in. In addition, the protection tube is
Since the structure has one vertical crack at each location, after opening the cracks one after another in the longitudinal direction and inserting the existing cable, the crack closes due to its own elasticity, so special crack connecting means etc. are not required. There are advantages to not doing so.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the implementation state of the method of the present invention;
Figures 2 (A) and (B) are a perspective view and an end view in the longitudinal direction of the protection tube used in this example, and Figure 3 is a perspective view of the crack opening/cable guide jig used in this example. FIG. 4 is a cross-sectional view showing an example of a conduit in which existing cables are protected by the method of this embodiment, and FIG. 5 is a cross-sectional view showing an example of a conventional conduit. 1... Existing cable, 2... Conduit, 4... Extension cable, 4... Protection tube, 4A... Crack, 5...
Crack opening/cable guide jig, 6... Crack opening frame, 7... Cable protection pipe, 8, 10...
・Spacer, 11... Retaining wire

Claims (1)

[Claims] In a method for protecting existing cables installed in a conduit, one
A protection tube having a single vertical crack at a location is successively opened from one end and placed over the existing cable, and the portion of the protection tube covered over the existing cable is sequentially supplied into the conduit. A method for protecting an existing cable in a conduit, comprising: protecting the outer periphery of the existing cable with the protection tube.