JP2000056162A - Optical cable junction box clamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clamp in the optical cable connection box with high reliability which hardly breaks its tension member even if an optical cable repeatedly swings. SOLUTION: The clamp 1 for fixing the tension member 2 of an optical cable 4, consisting principally of an optical fiber unit 6 and the tension member 2, in the connection box is characterized by that the fixation hole 3 of the clamp 1 for fixing the tension member 2 is expanded on the optical cable side so that the tension member 2 is loosely fit. Thus, the diameter expanded part 5 is formed in the tension member fixation hole 3 on the optical cable side, so the curvature of the tension member 2 accompanying the swinging of the optical cable is reduced to suppress the breakage of the tension member 2 where it exits from the clamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fixing hole for fixing a tension member constituting an optical cable of a clamp installed in an optical cable connection box.

[0002]

2. Description of the Related Art As shown in FIG. 3, for example, an optical fiber unit 6 in which a plurality of optical fibers are twisted together is further twisted by adding a tension member 2 to each other. Covered
Usually, an aluminum tube 8 is provided on this with a gap.
To connect such an optical cable 4 to another optical cable, a connection box 9 is used as shown in FIG. That is, at the end of the optical cable 4 pulled into the connection box 9, the aluminum tube 8 is removed, the polyethylene layer 7 is peeled off, the exposed tension member 2 is fixed to the tension member fixing hole of the clamp 1, and the optical fiber The unit 6 is inserted with a gap in the optical fiber unit insertion hole. In FIG. 4, reference numeral 10 denotes a metal fitting for holding the aluminum tube 8 for covering the optical cable, and reference numeral 11 denotes a connection portion of the optical fiber.

FIG. 5A is a front view of the clamp 1. FIG. The clamp 1 is obtained by tightening the clamp body 12 and the holding plate 13 with screws 14.
3, a tension member fixing hole 3 and an optical fiber unit insertion hole 15 are formed. Fig. 5 (b)
FIG. 3 is a plan view of the clamp 1 in which the tension member 2 is fixed in the tension member fixing hole 3 and the optical fiber unit 6 is inserted through the optical fiber unit insertion hole 15.
The inner diameter of the fixing hole 3 is slightly smaller than the outer diameter of the tension member 2, and the tension member 2 is fixed in the fixing hole 3 by tightening the screw 14. The fixing hole 3 is formed to have the same inner diameter over its entire length. The insertion hole 15 is formed slightly larger than the outer diameter of the optical fiber unit 6. Even after the screw 14 is tightened, a gap is formed between the optical fiber unit 6 and the insertion hole 15, and the inside of the insertion hole 15 is formed. Thus, stress that causes light loss is not applied to the optical fiber unit 6.

[0005] As shown in FIG.
In order to fix the tension member 2 in the fixing hole 3 and to insert the optical fiber unit 6 in the insertion hole 15, the tension member 2 is placed in a semicircular groove for the fixing hole formed on the upper surface of the clamp body 12, and the insertion is performed. The optical fiber unit 6 is placed in the semicircular groove for the hole, and the pressing plate 13 is placed on the optical fiber unit 6 with the upper surface of the main body 12 and the lower surface of the pressing plate 13 having the same groove formed on the mirror surface facing downward. 13 is screwed 14.

[0005]

Since the optical cable is inserted through the aluminum tube with a gap therebetween, the portion exposed from the aluminum tube swings back and forth and right and left during mounting work or inspection work. In some cases, when such swinging is repeated, the tension member 2 is sharply bent at a small curvature at the root portion 16 protruding from the fixing hole 3 of the clamp 1 as shown in FIG. 6, and this bending is repeated. In addition, the tension member 2 may be broken at the root portion 16, and sufficient reliability was not obtained. An object of the present invention is to provide a highly reliable clamp in an optical cable junction box in which a tension member is unlikely to be damaged even if an optical cable repeatedly swings.

[0006]

According to the present invention, there is provided a clamp for fixing the tension member of an optical cable having an optical fiber unit and a tension member as main components in a connection box. The optical cable connection box is characterized in that the optical cable side of the hole is enlarged to a size in which the tension member is loosely fitted.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1A is a front view of the clamp of the present invention as viewed from the optical cable side, and FIG. FIG. The fixing hole 3 for fixing the tension member 2 of the clamp 1 is formed such that the diameter of the optical cable side is enlarged to such an extent that the tension member 1 is loosely fitted. In FIG. 1, reference numeral 5 denotes an enlarged diameter portion. FIG. 2 is an explanatory diagram when the optical cable swings right and left. The tension member 2 bends at the root portion 17 protruding from the fixing hole 3 with the swing of the optical cable. Therefore tension member 2
Damage is suppressed.

In the present invention, the cross-sectional shape of the enlarged diameter portion of the fixing hole for fixing the tension member is not limited to the circular shape shown in FIG. The length of the enlarged diameter portion is desirably about ３ to ／ of the total length L of the fixing hole (see FIG. 1B). When the inner diameter of the enlarged diameter portion is formed to be narrow when the length of the enlarged diameter portion is short, and to be thick when the length of the enlarged diameter portion is long, the sharp bend can be suppressed. When the boundary between the fastening portion and the enlarged diameter portion of the fixing hole and the opening end of the enlarged diameter portion are tapered, the effect of preventing the tension member from being damaged is more reliably exhibited.

[0009]

As described above, in the clamp of the present invention, since the enlarged diameter portion is formed on the optical cable side of the tension member fixing hole, the bending of the tension member due to the swing of the optical cable becomes gentle. In addition, breakage at the base of the tension member coming out of the clamp is suppressed, and the reliability is excellent.

[Brief description of the drawings]

FIG. 1A is a front view showing an example of a clamp according to the present invention as viewed from an optical cable side, and FIG. 1B is a plan view showing a state in which a tension member is fixed to the clamp and an optical fiber unit is inserted.

FIG. 2 is an explanatory view of bending of a tension member in the clamp shown in FIG.

FIG. 3 is an explanatory diagram of an optical cable.

FIG. 4 is an explanatory diagram of an optical cable connection box.

FIG. 5A is a front view of a conventional clamp, and FIG. 5B is a plan view of a state in which a tension member is fixed to the clamp and an optical fiber unit is inserted.

FIG. 6 is an explanatory view of bending of a tension member in the clamp shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clamp 2 Tension member 3 Tension member fixing hole 4 Optical cable 5 Enlarged diameter portion of fixing hole 6 Optical fiber unit 7 Polyethylene layer 8 Aluminum tube 9 Optical cable connection box 10 Clamping fixture 11 Optical fiber connection section 12 Clamp body 13 Pressing plate 14 Screw 15 Optical fiber unit insertion hole 16 Root 17 Root

Claims (1)

[Claims] In a clamp for fixing the tension member of an optical cable having an optical fiber unit and a tension member as main constituent members in a connection box, the tension member is provided with a fixing hole for fixing the tension member of the clamp. A clamp in an optical cable connection box, the diameter of which is enlarged to a size to be fitted.