JPH04131803A - Pneumatic feeding pipe for wire body - Google Patents

Abstract

PURPOSE:To increase pneumatic feedable length greatly by providing >=1 projection on the internal surface of the pipe, used to pneumatically feed the wire body, continuously and spirally in the length direction. CONSTITUTION:Projections 2a - 2c are provided integrally on the inner wall surface of the pipe 1 continuously and spirally in the length direction. The air flow in the pipe 1 with the spiral projections 2a - 2b progresses spirally in the length direction, so the wire body gets on the flow and becomes easy to run at the center part and the possibility that the wire body contacts the internal wall surface of the pipe 1 decreases, so the frictional resistance is reduced. Further, the projections 2a - 2b are provided spirally on the wall surface of the pipe 1, so the resistance of the air flow on the surface of the wall 1 is large and the air easily flows at the center part where the resistance is small to flow at the maximum flow velocity at the center part. Consequently, the pneumatic feed distance can be increased greatly.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a pipe for pneumatic conveyance of a striated body, particularly to a conduit in which a striated body for communication such as an optical fiber is conveyed and laid by an air flow. This relates to the pneumatic feed pipe used.

(Prior Art) The technology of later transporting and laying a filamentous body such as an optical fiber into an existing empty pipe using an air stream has developed rapidly in recent years. Technologies such as those seen in the above have been put into practical use.

The air pressure pipes used in this technology are generally plastic circular pipes, and the inner surface of these pipes is made smooth to reduce the coefficient of friction.
Air is pumped through long pipes using air currents.

Even with such plastic tubes, it has been possible to force-feed and install optical fibers within the tube over a distance of more than 1000 m, but the longer the pumping distance, the better.

This is because if the pumping distance is long, a long optical fiber without a connection point can be laid over a long distance in a continuous length. However, as mentioned above, it is currently difficult to further extend the pumping distance.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and provides a new air pressure feeding pipe with the purpose of dramatically extending the conventional pressure feeding length. The purpose is to

(Means for Solving the Problems) The present invention provides a tube used for pneumatic transport of striatal bodies, comprising:
This is a striated pneumatic tube characterized by having one or more protrusions spirally and continuously provided on the inner surface of the tube in the longitudinal direction.

Note that air is not limited to natural air;
This refers to gases in general that can be used for pressure transport.

(Function) The pneumatic feeding tube of the present invention has a plurality of protrusions arranged in a spiral shape in the longitudinal direction on the inner surface of an ordinary circular tube.

Airflow flowing through a pipe with such spiral protrusions is
Since the filament moves in a spiral manner in the longitudinal direction, the filament body rides on the whirlpool, making it easier to travel in the center. Therefore, since the filament is less likely to rub against the inner wall surface of the tube, the frictional resistance is significantly reduced and the pumping distance is increased.

Moreover, the air flow has a maximum flow velocity at the center.

That is, since a plurality of protrusions are provided in a spiral shape on the pipe wall surface, the wall surface has a large resistance to air flow, and air flows easily through the center where resistance is low, and the flow velocity is maximum at the center. Therefore, the force acting on the filament body to travel through the center portion acts on the filament body, making it easier to travel through the center portion. Since this central part has the maximum flow velocity, the pumping distance is further extended.

Due to these two principles, the pumping distance is dramatically increased compared to conventional pipe lines.

(Embodiment) FIG. 1 is a perspective view of an embodiment of the air pressure feeding tube of the present invention. In the figure, 1 indicates the entire tube, and 2a.

2b and 2c are protrusions. The protrusions 2a, 2b, and 2c are integrally provided on the inner wall surface of the tube 1 and continue spirally in the longitudinal direction.

Such a pipe 1 is made of plastic material by using a pipe 1 having a protrusion (thick wall part) like the cross-sectional shape of the pipe 1 shown in FIG. By extrusion, the protrusions 2a, 2b, 2c can be formed integrally with the same material as the tube 1 when the tube 1 is molded.

FIGS. 2 and 3 are cross-sectional views of other embodiments of the air pressure feeding pipe of the present invention. In Figure 2, 2a, 2b, 2c
, 2d are the four protrusions 2a, 2b in Fig. 3.
Two protrusions are provided respectively. The longitudinal direction of the protrusion is spiral, as explained in FIG.

In this way, the number of protrusions in the present invention is arbitrary, and may be one or more.

Note that it is better that the top of the protrusion is not angular, and a shape in which the thick portion is somewhat emphasized is sufficient.

(Effects of the Invention) As is clear from the above description, according to the present invention, the presence of the spiral protrusion on the inner surface of the tube reduces the resistance to the filamentous body such as the optical fiber to be pumped, and efficiently transports it. can be transported, and the pumping distance can be dramatically increased.

If the pneumatic feeding tube according to the present invention is used in a so-called air blown fiber system (ABF), the single length of optical fiber can be increased, and economical effects can be achieved by shortening the pumping construction time and reducing the number of connection points. can. A reduction in the number of connection points is associated with a reduction in connection loss, and therefore has the effect of improving quality (lower transmission loss).

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the pneumatic feed pipe of the present invention;
FIGS. 2 and 3 are cross-sectional views of other embodiments of the air pressure feeding pipe of the present invention. 1... Entire tube 2a, 2b, 2c, 2d... Protrusions. Patent applicant Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] 1. A tube for pneumatic conveyance of striated bodies, characterized in that the inner surface of the tube is provided with one or more protrusions continuous in a spiral shape in the longitudinal direction.