JPH04372802A - Method and apparatus for detecting crushed position of pneumatic tube of optical fiber - Google Patents

Abstract

PURPOSE:To detect the crushed position of a tube readily by inserting a filament member having a spindle body having the specified outer diameter into the tube through which an optical fiber is inserted, feeding compressed air, sending the filament, and measuring the inserted length when the advance is stopped. CONSTITUTION:A crushed-position detecting apparatus is constituted of a spindle body 2 having the outer diameter D1 which is smaller than an inner diameter D0 of a tube 1 for an optical fiber and a piece of nylon string 4 whose one end is mounted on the spindle body 2 with an epoxy resin 3. The spindle body 2 is inserted into the tube 1. A connecting part 8 of a pressure container 7 is connected to an end part 11 of the tube 1. Compressed air is fed in the tube 1. The spindle body 2 is sent to the outlet side with the compressed air. The nylon string 4 which is unwound from a bobbin 10 is inserted into the tube 1. When there is a crushed part in the tube 1, the advance of the spindle body 2 is blocked, and the spindle body is stopped. The inserted length of the nylon string 4 at the time of stop is read, and the distance to the crushed position is judged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the collapsed position of an optical fiber pneumatic tube and an apparatus for carrying out the method.

0002

2. Description of the Related Art A known method for installing an optical fiber is to supply pressurized air into an optical fiber tube and use the propulsion force to insert the optical fiber. In such a tube, if the cable made up of the tubes is deformed due to external force during installation, the tube itself will also be crushed, making it difficult to insert the cable. In other words, when an optical fiber unit passes through a collapsed area, the frictional force increases and the propulsive force of the air pressure decreases.
The pumping speed of the unit decreases and the pumping length becomes extremely short compared to normal, which has a large negative impact on the pumping characteristics. Furthermore, if the inner diameter of the collapsed portion of the tube is smaller than the diameter of the optical fiber unit, further pressure feeding becomes impossible.

[0003] For this reason, conventionally, after laying the tube (cable) or before pumping the optical fiber unit, a ball or short optical fiber unit was passed through the tube to check whether the tube was crushed or not. .

0004

[Problems to be Solved by the Invention] However, although the above conventional method is effective in verifying that the tube is not crushed, if the tube is crushed, it is difficult to find where the bulb or short optical fiber unit is. It was not clear whether the tube had stopped, and it was not possible to detect where the tube had collapsed. For this reason, even if there is local collapse, the entire length is treated as unusable, resulting in unnecessary costs.

[0005] In order to detect the location of the collapse in order to avoid this, the only way to estimate the location of the collapse is by visually inspecting the entire length of the span of the installed tube, looking for any damage or flattening. Therefore, a considerable amount of effort is required to detect the collapsed position. In addition, if the tube cannot be detected from the outside or if the route is not visible to the naked eye, the entire length of the tube must be relined.

In view of the above circumstances, the present invention was devised to provide a method and apparatus that can easily and appropriately detect the collapsed position of a tube.

[0007]

[Means for Solving the Problems] The present invention involves inserting a filament member having a weight body having a predetermined outer diameter at its tip into a tube through which an optical fiber is inserted, and supplying pressurized air into the tube. The filament member is fed in one after another, and the inserted length is measured when the linear member stops advancing.

The present invention also provides an apparatus for carrying out the above method, which comprises a weight body having an outer diameter smaller than the inner diameter of the optical fiber tube, and a measuring wire having one end connected to the weight body. It is equipped with a strip member.

[0009]

[Operation] With the above structure, the weight sent into the tube by pressure air stops at a position where the inner diameter becomes narrow due to collapse. By measuring the length of the linear member sent in at that time, the distance from the insertion end of the tube to the collapsed position can be determined.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings.

First, an embodiment of the optical fiber pneumatic tube collapse position detecting device according to the present invention will be described with reference to FIGS. 1 to 3.

This device includes a weight body (test piece) 2 having an outer diameter D1 smaller than an inner diameter D0 of an optical fiber tube 1, and a test piece having one end attached to the weight body 2 with an epoxy resin 3. It is composed of nylon thread 4 as a filament member. The weight body outer diameter D1 should be set as the allowable diameter reduction limit value of the tube inner diameter D0.

The weight body 2 is a cylindrical body in which a core material 5 made of FRP is covered with high-density foamed polyethylene 6, and in this embodiment, the diameter d1 of the core material is 0.4 mm, which is determined by polyethylene. The outer diameter D1 of the weight body is 4.0 mm, and the length L is 15 mm. Further, the degree of foaming of the foamed polyethylene was approximately 50%. As shown in Fig. 3, the outer diameter d2 of the nylon thread 4 is 0.26 mm, and the surface
Colorings A1, A2, .

Next, an embodiment of the method for detecting the collapsed position of an optical fiber pneumatic feeding tube according to the present invention will be explained based on the effects of the above configuration.

First, in addition to the above-mentioned apparatus, as shown in FIG. 4, a pressure vessel 7 for pressure-feeding the weight body 2 and the nylon thread 4 is prepared. This container 7 has a substantially conical shape, and has a connecting portion 8 that fits into the tube 1 at the top, and connects to a pressurized air supply source (not shown) at the bottom to introduce pressurized air into the pressure container 7. A pressure applying port 9 is attached for this purpose.

As shown in FIG. 5, a bobbin 10 wound with a predetermined length of nylon thread 4 is rotatably housed in the pressure vessel 7. The collar diameter Φ of this bobbin 10 is, for example, about 50 mm.

When detecting the collapsed position of the tube 1 using these devices, first the bobbin 10 wound with the nylon thread 4 which is sufficiently longer than the entire length of the tube is stored in the pressure vessel 7, and the nylon thread 4 is The weight body 2 attached to the tip is inserted into the tube 1 whose collapse is to be checked. Then, the connecting part 8 of the pressure vessel 7 is connected to the end (pressure feeding port) 11 of the tube 1, and pressurized air is supplied into the tube 1 through the vessel 7. The weight body 2 is forced toward the outlet side by the driving force of this air pressure, and the nylon thread 4 unwound from the bobbin 10 is accordingly paid out into the tube 1. If the tube 1 is collapsed, the weight body 2 will be prevented from advancing because the inner diameter D0 at that location is reduced. At the point when this advancement is stopped, the identification colors A1, A2...An indicating the feeding length of the nylon thread 4 are applied.
is read through the tube or by separating the container 7 from the tube 1 to determine the distance to the collapsed position.

The inventors of the present invention attempted to detect the collapsed position in accordance with this embodiment. As an optical fiber pneumatic tube,
Prepare a tube 1 with a total length of 500 m, and hold it in a vise at a point 30 m from its end (outlet) so that the inner diameter D0 is approximately 3
An artificial collapse of mm was molded. Then, 6 kgf/cm2 of dry air was injected into the pressure air application port 9 of the pressure vessel 7, and the weight body 2 and the nylon thread 4 were fed into the tube 1 under pressure. As a result, it was determined that the approach of Plumb 2 was stopped after approximately 3 minutes and that it had reached the collapsed position. At that time, the nylon thread 4 was 450 to 500 m (0 to 5 m from the exit).
0 m ), which means that the collapsed position has been properly detected.

In this way, the nylon thread 4 whose one end is connected to the weight body 2 having an outer diameter D1 smaller than the inner diameter D0 of the tube 1 is suitably colored, and then inserted into the tube 1 using pressurized air. Since the insertion length when the tube stops advancing is identified, there is no need to inspect the appearance of the tube at all, and it is extremely easy to determine whether the tube is collapsed and to quickly detect its exact position.

Furthermore, by inserting the weight body 2 from both sides of the tube 1, the section where the collapse has occurred can be identified, and proper repair can be performed by inserting a normal tube. That is, it is possible to avoid relining the entire length, which has conventionally been necessary, and to eliminate waste of the tube 1, contributing to cost reduction in the optical fiber pressurized air insertion method.

In this embodiment, a cylindrical foam is used as the weight, but the weight may be spherical in shape, or an optical fiber unit may be used. Further, although the nylon thread is colored to identify the length, it may also be graduated. The length of the yarn to be paid out may also be measured by using an ordinary nylon thread without having to be specially formed for measuring length, and by passing it through an appropriate measuring device when the yarn is paid out from the bobbin.

[0022]

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are achieved.

(1) According to the method described in claim 1, the collapsed position can be detected extremely easily and appropriately.

(2) According to the apparatus according to claim 2, appropriate collapse position detection can be quickly achieved with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of an optical fiber pneumatic tube collapse position detection device according to the present invention.

FIG. 2 is a front sectional view showing the weight body of FIG. 1;

FIG. 3 is a perspective view of the nylon thread of FIG. 1;

FIG. 4 is an overall view of an apparatus for explaining an embodiment of a method for detecting a collapsed position of an optical fiber pneumatic feeding tube according to the present invention.

5 is a perspective view showing the bobbin in FIG. 4. FIG.

[Explanation of symbols]

1 Tube 2 Pyramid 4 Nylon thread (stripe member) D0 Inner diameter of tube D1 Outer diameter of weight body

Claims (2)

[Claims] Claim 1: A filamentous member having a weight having a predetermined outer diameter at its tip is inserted into a tube through which an optical fiber is inserted, and the filamentous member is sequentially fed by supplying pressurized air into the tube. , A method for detecting the collapsed position of an optical fiber pneumatic tube, characterized by measuring the insertion length when its advancement is stopped. 2. An optical fiber tube comprising: a weight body having an outer diameter smaller than the inner diameter of the optical fiber tube; and a linear member for measuring length, one end of which is connected to the weight body. A device for detecting the collapsed position of a feeding tube.