JP4357378B2 - Plastic resin tube end obturator - Google Patents

Description

  The present invention relates to a synthetic resin pipe end obturator for temporarily closing and sealing an end portion of a cable protection pipe laid in a construction of laying an underground cable.

  In recent years, communication cables such as optical fiber cables and power cables are increasingly buried underground. In such underground cables, the cable is disposed in a protective tube made of a synthetic resin such as vinyl chloride resin, the protective tube has a receiving port with an enlarged diameter at one end, and an insertion port at the other end. Are sealed and joined through rubber rings, and are sequentially piped. After the construction of a certain section is completed, until the next extension work begins, the receiving side opening of the last protective pipe laid is temporarily sealed and closed, and groundwater and earth and sand flow into the protective pipe buried underground It is necessary to preserve so that it does not.

As such a tube end obturator, in order to use a sealing joint by a rubber ring built in the opening of the protective tube that is open, and to suppress the manufacturing cost of the obturator, A short tube made of synthetic resin with the same diameter is used by inserting and closing a disc whose outer diameter matches the inner diameter of the short tube, and this is inserted into the receiving port of the protective tube. The mouth was blocked.
However, the obturator that is simply bonded by inserting a disc into such a short pipe has a slight difference in the inner diameter of the short pipe, resulting in variations in the bonding strength. It was difficult to completely prevent the inflow of groundwater and earth and sand into the protective pipe.

  The present invention has been made to solve the above-described problems, and provides a synthetic resin tube end obturator capable of reliably closing and sealing the open end of a cable protection tube buried underground. It is for the purpose.

As a result of intensive research, the inventors have cut the inner peripheral surface of the end portion of the short pipe to form a recessed portion having a diameter larger than the inner diameter of the short tube, and a disc is fitted and bonded to the recessed portion. As a result, the inventors have found that the above problems can be solved, and completed the present invention.
That is, the gist of the present invention is that the diameter of the concave portion is substantially the same as the diameter of the concave portion formed on the inner peripheral surface of one end of the short tube having the same outer diameter as the cable protection tube. The synthetic resin pipe end obturator of the underground buried cable protective pipe formed by inserting and bonding a disk having
Further, in the synthetic resin tube end obturator, a fitting groove having a slightly larger diameter than the short tube end side is formed on the back side of the short tube of the recessed portion, and the insertion side of the disc is It is preferable that an annular convex portion having substantially the same diameter as the diameter of the fitting groove is formed and the fitting groove and the annular convex portion are fitted.

  According to the present invention, since the recessed portion is formed by cutting on the inner peripheral surface of one end of the short tube constituting the tube end obturator, the inner diameter of the short tube end into which the disk is inserted is made to have a constant dimension. Thus, reliable bonding without variation in bonding strength is possible. In addition, if the annular groove formed on the disk insertion side is fitted into the fitting groove formed on the back side of the short tube of the recessed portion, it is possible to reliably prevent the disk from coming out of the short tube. More preferred. By inserting the tube end obturator configured in this way into the opening receiving opening of the cable protection tube and joining the rubber ring, the end portion of the cable protection tube can be securely sealed for a long period of time.

  FIG. 1 shows a longitudinal sectional view of a short pipe and a disk constituting a synthetic resin pipe end obturator of the underground buried cable protective pipe of the present invention, and FIG. 2 shows the structure of the cable protective pipe.

The short tube 2 constituting the tube end obturator 1 shown in FIG. 1 is a chloride tube having the same diameter as the material of the short tube 2 when, for example, a standard vinyl chloride resin tube is used as the original tube for the cable protection tube. The original tube made of vinyl resin can be cut into a dimension slightly longer than the length of the receiving port of the protective tube, and in this case, the disc 3 is preferably made of the same vinyl chloride resin.
Recessed portion 21 of the inner diameter than the diameter of the short tube 2 at one end in the peripheral surface Litan by the cutting in the tube 2 is formed slightly larger than the short tube end portion side to the short tube inner side of the recessed portion 21 A fitting groove 21a having a diameter is formed. The step is about 0.1 to 0.5 mm.
Further, the outer peripheral surface at the tip of the short tube 2 on the recessed portion 21 side is chamfered to form an annular inclined portion 22. The annular inclined portion 22 is formed to facilitate insertion when the tube end obturator 1 is inserted into the opening of the cable protection tube, and the side where the recessed portion 21 of the short tube 2 is not formed. The tip outer peripheral surface may be chamfered.
The disc 3 has a diameter substantially the same as the diameter of the recessed portion 21, has a thickness approximately the same as the length (depth) of the recessed portion 21, and is fitted to the insertion side of the disc 3. An annular convex portion 31 having substantially the same diameter as the groove 21a is formed, and a chamfered portion 31a is formed on the outer periphery of the tip.

  Taking the case where the nominal diameter of the short pipe 2 is 250 mm as an example, the preferred dimensions of the diameter of each part are 250.0 ± 0.1 for the recessed part 21 and 250.4 ± 0.1 for the fitting groove 21a, respectively. The disc 3 has a very small dimensional difference of about 250.1 ± 0.1 and the annular convex portion 31 has about 250.5 ± 0.1, and requires a high degree of dimensional accuracy. The difference between the diameter of the recessed portion 21 and the inner diameter of the short tube 2 with respect to the wall thickness of 12.7 mm of the short tube 2 is designed to be 4.2 mm, for example, and the length of the recessed portion 21 and the fitting groove 21a ( Depth) is designed to be 21 mm and 14.5 mm, respectively, as an example.

Regarding the method of manufacturing the obturator 1 by inserting the disc 3 into the short tube 2 and fixing it with an adhesive, first the inner surface of the recessed portion 21 formed at one end of the short tube 2 or the disc 3 Adhesive is also applied to the outer peripheral surface, and the disc 3 is pushed into the recessed portion 21 of the short tube 2 from the annular convex portion 31 side. The diameter of the annular convex portion 31 of the disc 3 is slightly larger than the inner diameter of the distal end side of the recessed portion 21 of the short tube 2, but a chamfered portion 31 a is formed on the outer periphery of the annular convex portion 31. When pushed in, the short tube 2 is elastically deformed by the pressing force into which the disc 3 is pushed, and the diameter is somewhat expanded. In the disc 3 pushed into the recessed portion 21 of the short tube 2, the annular convex portion 31 is fitted into the fitting groove 21a.
Since the disc 3 is pushed in while rubbing the inner wall of the recessed portion 21 that has been slightly swollen with the solvent contained in the adhesive, the short tube 2 and the disc 3 are joined smoothly and firmly.
In addition, since the synthetic resin original pipe of the short pipe 2 is usually extruded by the outer diameter regulation, the outer circumference dimension is finished relatively accurately, but the inner circumference shape that is not regulated is not necessarily constant, Since the concave portion 21 of the short tube 2 into which the plate 3 is inserted is precisely finished by cutting so that the inner peripheral surface matches the outer peripheral surface of the disc 3, there is no variation in the adhesive strength.

  On the other hand, as shown in FIG. 2, the cable protection tube 4 is made of a synthetic resin, for example, a vinyl chloride resin standard tube as an original tube, one end of which is enlarged in diameter and a receiving port 41 is formed. A rubber ring 43 is accommodated in an annular groove 42 formed on the inner peripheral surface of the receiving port 41, and the receiving port 41 and the insertion port of the protective tube 4 inserted therein are sealed and joined by the rubber ring 43. .

  The cable protective tube 4 is sequentially piped by receiving and joining, and the pipe end obturator 1 configured as described above is formed on the outer peripheral surface of the distal end of the receiving port 41 of the protective pipe 4 at the end of the pipe. Insert from the inclined portion 22 side and push until the tip of the tube end obturator 1 reaches the back end of the receiving port 41. Since a synthetic resin tube having the same outer diameter as the cable protection tube 4 is used for the original tube of the short tube 2 constituting the tube end obturator 1, the connection between the receiving port 41 of the protection tube 4 and the tube end obturator 1 is as follows. The sealing performance by the rubber ring of the same level as the receiving and joining of the protective tubes 4 is exhibited.

It is a longitudinal cross-sectional view of the short pipe and disc which comprise the synthetic resin pipe end obturator of the underground buried cable protection pipe of this invention. It is a partial longitudinal cross-sectional view which shows the structure of an underground buried cable protective tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pipe end obturator 2 ... Short pipe 21 ... Recessed part 21a ... Fitting groove 22 ... Inclined part 3 ... Disc 31 ... Annular convex part 31a ... Chamfered part 4 ... Cable protection tube 41 ... Receiving port 42 ... Rubber ring storage groove 43 ... Rubber ring

Claims (2)

A plastic resin tube end obturator that closes the end of the cable protection tube by inserting it into the rubber ring socket of the cable protection tube,
A short pipe having the same outer diameter as the cable protection pipe ,
A recess formed in an inner peripheral surface of one end of the short pipe by cutting an inner peripheral surface including a pipe end of the short pipe, and having a diameter larger than the inner diameter of the short pipe; and
The have a diameter approximately the same diameter of the recess, it comprises a disc that will be fitted bonded to the recessed portion, the synthetic resin pipe end obturator. Wherein formed on the short pipe inner side of the recessed portion, a fitting groove having a large Kina径 slightly than the short tube end side, and is formed on the insertion side of the disc, substantially equal to the diameter of the fitting groove It has a diameter, further comprising an annular protrusion fitted into the fitting groove, the synthetic resin pipe end obturator of claim 1.

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